I believe that there are people who experience no sexual feelings ever, which is abnormal enough to have a name for it, but as for all the rest I don't see how those things qualify as distinct sexualities.

I think it came around because certain people felt disconnection towards sex when compared to society as whole. I don't mean just the "act of sex", we have a culture around sex that is difficult to understand if you're in the ace spectrum. For instance a demisexual person could go to the club and don't feel "the horny" when their friends talk about being horny and etc, the demisexual is disconnected from that even if they also have sexual relationships and feel "the horny".

They put all these same people on the "ace spectrum", which means an aromantic individual (don't feel romantic attraction) fits even if they can have all the other human sexual characteristics when we disregard romance. A good way to look at it is really just on the mindset of "lacking certain characteristics of human sexuality" and it makes it very easy to understand. A demisexual only feels the horny if they have a emotional bond, instead of feeling arousal towards pretty people in general.

These resources are important because these people can get frustrated with the "disconnection" I mentioned.

Not getting aroused unless you have a deep connection with someone isn't that weird

I wouldn't call it weird (queer communities don't consider themselves weird ofc and hate being called that). However it's a defining characteristic of a demisexual person that isn't found on most people.

and grey just sounds like low libido, which is also pretty normal

It could be. I'm not gonna deny some average joes are appropriating asexuality. But there's definitely actual asexuals who fit in the grey label.

it just seems unnecessary to give it a label and a flag unless the purpose behind it is to feel like part of the club.

Certain people agree with this take, asexuals included. Look up "Queer Heterosexuality".

However like I mentioned, I do think this exist. Wether it's a mental illness or a mental deficent on individuals or whatever, these resources are important to help them live their lifes. It's not like being a homosexual where you can have gay sex and gay marriage and that's a easy answer. People in the ace spectrum are extremely rare (I don't know how rare when compared to dysphoria) and the asexual awareness program has a forum that acts as a sort of "club" for people to give advice to each other. I find it a fair cause that most people could get behind.