Companies fiddling with speech is perfectly legal. No one is obliged to give a soapbox to anyone. Companies curbing speech they don't want to host is not an infringment on speech, legally (in the US, at least).
An anaolgy might be: You offer your front yard for people to put signs in. Someone decides to put a Nazi flag sign in your yard. You are within your rights to remove that sign, even though you made a general offer for anyone to put signs in your yard.
People (again, in the US) very often conflate this kind of situation - a private entity curbing speech that they don't want to be associated with - with the First Amendment of the US Constitution (my emphasis):
Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.
Free speech, in the US, is about whether Congress, and as has been interpreted by the courts, the government generally, may abridge the freedom of speech. The government may not.
Even so, free speech is not absolute. It remains against the law for individuals to use speech to incite violence, or to incite an emergency reaction where no emergency exists ("Fire!" in a crowded theater), for two examples. Another example would be communicating classified information to people who are not authorized to have said information.
There remains a real conflict about free speech, and it's the elmination of the commons. When the Constitution was written and ratified, the First Amendment protection of speech was more effective, because the way you would get your speech to a large number of people was via distribution of pamphlets and just speaking aloud in public spaces, where passers-by were walking. The landscape is very different today, where "public" messaging happens on the conduits provided by private companies - who, as we've learned, are not legally obliged to carry that speech. In fact, those private companies operating "open forums" can be held responsible for failing to moderate speech which runs afoul of legal limitations on speech.
The internet is definitely a huge change around speech, but the degradation of public spaces brought on by shopping malls - which are private property - had the same kind of effect. The fact that we tend to spend more time in our private homes, travel in the bubbles of our private vehicles, and do our personal business entirely on private property effectively reduces the public space available to exercise our own free speech effectively, or be exposed to others' speech similarly.
I'll go and look at how my recent comments and submissions are doing, but that's more to get a sense of how my outlook aligns with the outlook of the general readership. And when the alignment is off, I'll look at other comments to see what is getting traction.
By this process, its become clear to me that the outlook of Reddit The Userbase (as opposed to Reddit The Company) has become much younger in recent years. All too often, when my positions are heavily downvoted, neighboring comments expressing more popular (populist?) positions make me think, "Yeah, I used to think that ... thirty plus years ago."
That’s where tech companies start to get a justification to fiddle with speech.
Which implies that companies need a "justification," which further implies that companies "fiddling with speech" needs to be "justified," as though "unjustified fiddling with speech by companies" is, or should be, disallowed.
Later, you said:
Free speech usually means that you have freedom to express yourself, ...
That might be colloquially accurate, but it's misleading in the context of private companies acting as platforms for speech, in the US (I know I have beat that drum plenty, but it's necessary).
Infringement of freedoms is met with legal consequences. Since private entities are not oblligated to be a platform for any speech, whether that's a forum on the internet or other people's signs in your front yard, there are no legal consequences when those private entities curb the speech in the space they provide for speech. The discussions around this situation generally carry a subtext of "something should be done about this," and because of the conflation of colloquial vs legal "free speech," it's easy for that "something" to feel like "companies shouldn't be able to do that," with legal consequences.
Who is talking about it being illegal?
People rightly recognize that there is a problem with the diminishing ability for people to express themselves, and conversations about that usually misidentify the problem as being with the operators of private spaces where so much speech is today exercised. Any solution which grants and protects individual rights is necessarily a legal solution. So, while maybe nobody is saying the words "It should be illegal for companies to curb speech on the platforms they operate," the discussion is about a legal remedy.
I was trying to describe that the problem is more likely the degradation of the public commons. The relative absence of public spaces in which speech can be effectively transmitted drives people's speech to private spaces, and those private spaces come with much greater limitations on speech. While I don't have a specific solution to offer for that problem, I have to think it must include creating or reinvigorating public commons.
Let's not forget that even the 20-episode season greats had their fair share of real stinker episodes, those stinkers increasing in frequency as the series dragged on several seasons longer than it should have due to sheer momentum. And that a huge proportion of 20 episode season television series just sucked and were forgotten about.
We've also moved beyond the three-camera stage plays with very few sets to television shows where one episode is shot on more sets than Friends used for its entire run - because it makes better television. Episodes are also longer than 22 minutes now. (That's what YouTube is for.) These factors demand a lot more effort, which means there's not enough time or labor to pull together 20 episodes in a year.
Call of the void. My understanding is that it's your brain inventing risky scenarios so that you can shrink from them in revulsion, as practice for "don't do that."
My point being that there are great numbers of adults people who still literally believe in the organized religion of their choice. Those people do not "pull back the curtain" for their children when they come of age; they continue to propagate the religion as truth.