> StackExchange had ridiculously high barriers to participation

Only in terms of asking new questions, because this was never intended to be the primary use of the site. The entire point of the model is that one person asking a good question could save many others the effort of asking — and answering. But everyone who made an account had permission right off the bat to propose edits to questions and answers, for example.

> making it inclusive to the long-time users on the site, but exclusive to the newbie participants who found themselves blocked for asking questions.

Rounding it off like this is missing the point, and doesn't demonstrate understanding of or consideration towards the underlying rationale.

> They slowly killed the site in this manner.

It was never supposed to get even remotely as big as it did. It is entirely unreasonable to have ended up with 24 million open, publicly visible questions about programming, when that is over triple the number of Wikipedia articles about literally anything noteworthy.

> knowing I'd have to consider all the ways a bully eager to use their powers might misunderstand me

I can guarantee you that the overwhelming majority of such action is not motivated by "eagerness to use powers", not an attempt at "bullying", and not the result of "misunderstanding" the thrust of the question.

It is a result of misunderstanding what kind of questions the site wants, and why it wants that kind of question.

> I can't imagine asking a question there without having had lurked for longer than a typical Bachelor's + Masters program.

Reading through, for example, https://meta.stackoverflow.com/questions/433897 and understanding what is written there is literally all that is required.