I hadn't thought to call it gatekeeping, but this annoyed me too. People should say, "This is how I am going to use this word right now while I explain this," and not, "To understand what I'm explaining you first need to realize that the correct use of this word in this one limited way I'm using it right now."
I've noticed a LOT of discussion on HN around this theme in the past week -- that so much trouble happens when people disagree on what words mean and refuse to be more specific. This is a good example of one way this kind of thing starts, which is that someone tries to dictate the meanings of words and categories to advantage of their own beliefs relative to the beliefs they oppose. You see this everywhere from politics to business to debates over whether hot dogs count as sandwiches or not.
I've encountered this going back to the beginning of my career with basic software engineering terminology. Different experts have different definitions of terms like "unit test" or "user story," and they think the differences are important, for good reasons, so they promote their own definitions. Some software engineer learns one expert's definitions and they become impossible to talk to because they keep correcting you about what words mean. They don't understand that there are differing expert opinions, and that the experts who promote the definitions they use are reasonable people who converse and debate with other experts who use different definitions. But when I say "in the past I've found it useful to think about it this way" they just say "but that's not a unit test" or "that's not a user story" and I say "I think in these circumstances this is the kind of user story that serves us best to succeed on this project, for these reasons" and they just say "but that's not a user story because a user story has to..." and the conversation goes nowhere.
I learned way too late in my career that just because your company's self-appointed authority on some software engineering concept makes it sound pedantic and useless doesn't mean it is. Chase it down to the source, and you'll likely find a thoughtful and nuanced take on it.