YSK that the number of users that is shown in the community overview is the numbers of users from your instance that are subscribed. So in your case that is reddhat.online. (Doesn’t mean that the communities you’re linking to are big, but it does mean that you’re not seeing the full picture. There are places that do contain more general information, like browse.feddit.de.
For me Mastodon is still growing and getting more interesting, with more and more formal institutions joining (newspapers, NGOs, government institutions etc.).
With a GUI you also don’t know what it does. Its the same situation, you just click a button that runs the code instead of copying and pasting the code in the terminal. (And I would say the latter is safer because it is more transparent (for those who want to figure it out)).