I don't like being called a guy or a dude or a fellow. PARTICULARLY in gaming spaces.
It's not about offense.
I'm not offended to be called one of the guys. Doesn't bother me at all.
If you come to my house and are trying to get everyone's attention, saying "hey guys!" that doesn't make me blink an eye.
But context matters. Context is everything.
Women have had a very hard time in the tabletop roleplaying games hobby. Their contributions have been historically ignored, erased, and looked over. Their participation has been resisted and mocked by men. Currently, women are starting to come into their own, AND YET there are FAR TOO MANY men who are still incredibly dismissive of women's experiences, expertise, and influence. FAR TOO MANY of them are actively trying to chase women out of this hobby.
Non-binary and other gendered persons have had it even worse. Unspeakably so.
So when one addresses a bunch of male, female, non-binary, and other gendered persons as:
in the tabletop roleplaying hobby or other place where women have had a tough time (I'm looking at you, Science), it FURTHER erases the contributions and the presence of women and other non-men. Women who have persisted and suffered through decades of abuse and invalidation in this hobby. It takes us one step back towards the 1970s and 1980s and truthfully the 1990s when it was REALLY hella hard to be a woman in this hobby.
I know it was hard. I lived through those years. I saw it first hand.
Guys isn't a word that indicates women. Dude isn't a word that indicates women. Fellow isn't a word that indicates women.
I dare you to post the appropriate one of these statements on Twitter or Facebook with NO EXPLANATION.
If you're a straight man, tell your friends "I am REALLY attracted to guys".
If you're a straight woman, tell your friends "I am really NOT attracted to dudes".
See what happens. Run the experiment. Don't cheat and explain it.
People will, the vast majority of the time, think you're talking about men... because "guys" and "dudes" are not words that indicate a woman.
It takes barely any time or effort to address a group of people in this hobby as:
Players and DMs
Or anything else that includes traditionally marginalized people in this hobby. It's polite. It's inclusive. Mistakes happen. That's fine. It's okay. But if you call a group of gamers "guys" and if someone says "hey, you know what, there are a LOT of non-guys here."
You have some choices.
You might say, "You're right. HEY Y'ALL!" Or maybe you wanna argue about it, which indicates that you just don't give a damn about women and other non-men in this hobby.