I view this in a more optimistic light. Computers and the Internet are complex systems, and not everyone needs to nor wants to understand all the intricacies of them. Sure, we could format our reports and letters via LaTeX, but frankly, any word processing software that wraps the functionality into a few easy to understand buttons does the trick too for most of us.
Online platforms that allow people to communicate within a wide range of models (1:1, 1:many, many:many, private, open, open to friends-of-friends, and so on) need to give users feedback and information on the fly so they know which mode and setting is active, and if it is appropriate.
If the platform caters to just one type of audience, and centers around a specific interest or topic, that informs the audience directly on how to behave. And people can lurk before participating, so they follow the existing examples.
With an open and global platform, it is a lot harder to set these existing examples, because one does not know, with which subset the new member will interact first, nor with which topic.
Good UX guides them, informs the newbies about the presets and their reasoning, and so on. Imagine you see someone else post racist hate speech. Depending on which options and how visible these are, you might just put that person on an “ignore” list and move on. Or you actively block the racist. Or maybe report the content to moderators, but leave the person unblocked, because doing both requires too much effort through the interface.
UX can make or break how people interact with each other as a community, and especially with open source projects it is often enough added as an afterthought. (Which is not meant to diss open source.)