I think the only reason those specifically are most well known, is because they capture popular imagination.
Basically, because it’s impossible to see inside black holes to know what’s going on, there’s very few ways to validate ideas. Therefore, outside of a select number of external observational techniques (like radio signals and gravitational waves) to place some limitations, ideas about what happens beyons the event horizon are in the realm of pure math, which people don’t care about unless it either A. Verifiable, or B. Just sounds really cool.
Black Hole hypotheses therefore tend to go one of a few ways:
Scenario 1
Scientist A: Hey if you use this math, black holes can do this thing
Scientist B: That requires this other thing which isn’t true, to be true, and/or breaks this fundamental law
Scientist A: This hypothesis is my precious brain baby and if you talk shit about it I will shatter your knees
Scenario 2
Scientist A: Hey if you use this math, black holes can do this thing
Scientist B: That requires an assumption we can’t, or have yet to, verify is true (almost always somehow related to string theory)
Scientist A: This hypothesis is my precious brain baby and if you talk shit about it I will shatter your knees
Scenario 3:
Scientist A: Hey if you use this math, black holes can do this thing
Scientist B: Okay the math checks out as one of X number of possibilities with that same math, but there’s know way to tell which, if any of these would be true (equations with multiple valid solutions, almost always related to spacetime topology)
Scientist A: Heehee numbers do funni
ETA: The specific subcategories of hypotheses you mentioned also have an inherent advantage of not having to deal with singularities. Why that’s good: Einstein’s theories say infinite density impossible. With singularity, can’t connect quantum theory to relativity theory. No quantum gravity make math bb’s big sad. Solution? Instead of squoosh matter really tiny, just send it somewhere else! They aren’t the only frameworks that avoid singularities, but definitely the coolest sounding and least complicated
I can’t remember if it was a youtube video or a paper or an article or what, but I saw something explaining that, based on one interpretation of Einsteins equations, past the point of singularity, space and time invert. This would mean that the longer the black hole exists around in “our” universe (in absolute terms), the larger it becomes on the inside, and the larger it gets on the outside, the longer the inside universe would persist. I feel like you would have liked it, if only I could remember what it was. :(
The thing I saw postulated both that the universe would reuse the matter the black hole absorbed, and that there would be infinite branching universes since each would develop their own black holes, but then you have an issue with regards to running out of matter at some point. Though I guess that could be solved if you assume every black hole must converge at the end of their containing universe’s lifespan, and all matter would be reused in whatever blackhole absorbs the blackhole containing that parent universe? Oh hey, we’re back to fractals again!
Personally I’m a fan of the idea of black holes as topological stars that fall in line with string theory, but there have been so many hypothetical frameworks coming out in recent years that are just fascinating to think about.
I get the objective need for the /s in this particular context, but we absolutely should add “using /s when the sarcasm should be obvious for anyone with basic reading comprehension skills” to the list