Validation is actually a normal part of life as a social species. The very reason you are expressing your opinion on this forum is that you seek validation. It's OK - it's normal.
"Well I don't care who thinks I'm "valid" as a lesbian"
You might if there were people trying to make it so that you couldn't marry your partner for example because they don't think that your sexual orientation is valid.
How old are you, Shizuku? Because unless you're quite young, you're surely able to remember a time when 'validation' did not get used in that way. Very recently, in fact! You know perfectly well it's used to mean emotional or identity affirmation. Feelings. Worth as a person.
I'm not exactly ancient (early forties), but when I was young people didn't expect others to be constantly "validating" them all the time. The idea was that you were someone with a self and self-esteem, you might even think of yourself as having an 'identity', but that it wasn't anyone else's job to be going about constantly reflecting your feeling and self-esteem back at you. That sounds in fact pretty needy and neurotic, requiring everyone around you to be always "validating" you.
When I was a teenage lesbian, I wanted rights and representation, but it would have astonished me that it was other people's business to be "validating" me all the time. What happened to developing a strong sense of self, purpose and character? Yes, people need social affirmation, solidarity and recognition; but the idea that people must constantly be emotionally "validated" in their "identity" is a very recent formulation. (I don't believe in "identity" either, by the way - at least, not in the way you think of it.)
Also - I'm not expressing my opinion on this forum to seek emotional validation - I'm engaging in rhetorical and intellectual argument. That isn't anything to do with affirming feelings or identities (though there's a tendency more and more for people to mistake that it is). Intellectual argument is rational. For me, this means feelings and validation are not involved. I'm engaging in debate, not therapy. Sure, you can feel differently; but don't assume that people's challenges to your concepts and ideas are necessarily based in either identity or emotion.