@PeripheralVision i mean, sure, there are some niche situations where a genuinely likeable person struggles with forming human connection due to due to certain disorders, but i think that's only applicable to small minority of people who are lonely these days. since op didn't mention having any condition like that, it is fair to assume that what i said applies to him.
and here's the thing, when i said that i'm speaking from personal experience, i was referring to both myself being an unlikable person and the fact that i've spent a lot of time doomscrolling on online forums full of people like myself, such as subreddits full of lonely people or 4chan boards like /r9k/. interacting with people like that made it abundantly clear to me that people such as myself are friendless and alone simply because there's hardly any reason to be friends with us. we're neurotic, hard to relate to, have specific and unusual interests, and are socially inept. why would one want to be friends with such a person?
i also don't buy into a lot of mental disorders actually being real. there's a direct correlation between what psychology deems to be a disorder and what society deems normal behavior. stuff like homosexuality was once considered a disorder for no reason other than the fact that society disliked homosexuals. and it wasn't rigorous research that helped psychologists come to the conclusion that homosexuality is not a disorder, they simply stopped calling it a disorder because society started accepting homosexuals. that's just one random example. one of the things that supposedly makes something a disorder is whether or not it causes mental suffering, which i find hilarious. of course if society discriminates against certain people, they will end up suffering. it wasn't them being different that caused their suffering, but rather it was being discriminated against by society that caused them suffering. i think many (but not all) disorders work the same way. if society were more accommodating towards people with certain disorders, you would likely find that they no longer experience as much distress, and if they no longer experience that much distress, then is it truly a disorder? remember, distress and deviance are two of the 5ds of psychology.
but anyhow, all of that is just hypothetical. i don't actually think normal people have an obligation to accept people who aren't normal. here's a story of my own. i started working this summer because my mother got tired of me being a useless neet for several years. when i started working, i was initially placed in a position where i had to talk to my coworkers several times a day. there was a lot of friendly small talk involved between my coworkers. they tried to make friendly small talk with me as well, but they all sooner or later came to the conclusion that there was something innately wrong with me. i had weird mannerisms such as not making eye contact and hiding my face, i couldn't hold a conversation about normal topics because i knew nothing about them since all my knowledge comes from doomscrolling 24/7, i couldn't relate to any of them and none of them could relate to me, i'm stupid and i often misunderstood what they were asking me, i'm ashamed of myself so i often times gave them vague and nondescript answers about myself as a person because i feared judgment, i struggle to speak my native language because i spend all my free time on english (my native language is not english) sites, i have a very flat and monotone voice which puts people off, i'm unattractive physically which puts people off even more, etc. i could go on all day of all the things that were wrong with me and i honestly don't believe that my coworkers were wrong for eventually not wanting to associate with me. it's understandable why they would eventually avoid me. i was always very bad socially and years of social isolation as a neet made things even worse to the point where i think i'm beyond repair. i tried my hardest to talk to them but i couldn't. luckily, they later moved me to a different position that hardly involves any interaction. i just work by myself now and only have to talk to my boss very briefly like once a week. i will try to keep this job for as long as i can because i'd probably have a panic attack if i had to have a job that involves talking to people again. this whole experience made me feel like i'm not even a human being anymore. it made me feel terrible, but i still don't hold any resentment towards anyone because as you said, you have to offer something of value to someone to form meaningful relationships with them. i have nothing to offer. i ultimately just drag people down because i'm simply not normal. i have nobody to blame other than myself. i certainly won't blame stupid meme disorders for it.
with all of this in mind, i have chosen to isolate myself from everyone for the rest of my life. i will never seek any sort of human connection ever again, neither online or offline. the only person i will talk to properly in real life is my mother, and once she passes, i'll truly be alone. i will try to fill the void by posting stupid shit on online forums, doomscrolling, and consooming anime and video games, although doing that progressively getting harder due to my very shortening attention span. i'm not going to pretend that this doesn't hurt me emotionally because it does, but i think i can eventually rewire my brain to not crave any human connection. that's what i'm hoping for at least. i haven't had friends since the age of 12 and i'm still alive, so it must be possible.
anyway, i don't know why the fuck i wrote all this. everything i said probably sounds straight up idiotic. you can probably make a copypasta out of this.