"guys" is a gendered term? I mean, i've used it in relation to men, but I've also used it in a completely unisex type way... as a colloquial "hey people"... huh... the things you learn... are people truly offended by "guys"?

Well, it's not always about being offended... it can also be about feeling, or not feeling, included. Personally, if something is addressed to 'guys', I tend to think it's not meant for me as I'm not a guy.
Keep in mind that we're not all native speakers of English, so we're not all familiar with your colloquialisms.

It's not about taking offense or not taking offense by any particular person, it's about making sure the community is open and welcoming to everyone. Previous discussions in the community have shown that some people do consider "guys" a gendered term, and some don't.

I guess every time this issue comes up I feel like I'm "less" included because I am not free to speak in a way that comes naturally to me. And I've never thought that my natural way of speaking is particularly unwelcoming to other people.

I guess this is just one time too many. As much as I love my cup, I think I'd rather not be a part of a community that is constantly reminding me that the way I talk is unacceptable. Best of luck to all ladies, gentlemen, transgender, genderqueer, female, male, androgynous, and all other humans and others that I have not included.

I'm very sorry that you feel that way. Best of luck to you.