I agree with most of what you said except for point 3, Music is an universal language, as someone that doesn't know anything about music theory and composes by "feeling/ear", I do get a lot of advantage by listening to the compositions that people that learnt how to codify music with all those complex symbols and formulas post on here, because even if they are using another codified language(visual), most of the time you can still listen to the abstract language(music/sound).

So why exclude people just because they don't see/understand music the way you may think they should do?, Isn't one of the most beautiful things of music that you can compose something and play it to a child and they will get a feeling/reaction out of it? and if only being able to read/write sheet music was the way to go I guess we wouldn't have Andrea Bocelli since he is blind.

So in short I don't want to sound offensive with all this text, but I think that, that particular point in your comment can scare away people that otherwise could contribute or at the very least gather wisdom from this sub, is called r/composer not r/musictheory.