That's because you're at a similar level in your support skill to your skill in other lanes.
Erm...no, I'm not.
I am toplane main, and I like playing mid.
I have a core roster of 5 champs that I play well in almost any matchup toplane, and have a huge impact with in my games, and I can play several others picks which I use situationally. Top is by far my most played lane. I spend a huge amount of time researching champs, developments, matchups, watch streams and videos by pros, the whole deal.
I am also an avid midlaner, playing safe, reliable but impactful scaling picks. I also do really well with trickpicking toplaners, mostly tanks, into midlane. My second most played lane.
#I never play support unless I have to.
I have most of the champions, yes, but that's because I simply collected almost all the champions over the years. I have no skins for support champions. I have a single rune-page set up secifically for support, and that one only really works with tanksupps. I can play 1 (ONE) support champion.
And that one champ is
A "point and click" champion that a monkey could play. She kinda plays into my wheelhouse, because shes a tank, and I like playing tanky bruisers and tanks.
I know little and less about managing the botlane, or support-roaming, nor do I know the matchups. I do what feels right and go by gut feeling.
But the dfference between you and me, is that I don't give up from the start when I have to play it. I grab the one champ I know what the hell the abilities do, I build the same things I know to work, and I do the same things in every matchup.
And whaddaya know: It works. I may not carry the game, but I sure as hell am not a burden to my team, pull my own weight, and make myself carryable by them.
Nope, it's quite sad that you're so delusionally idealistic tbh, that's not how it works in the real world.
Wrong, that's exactly how it works in the real world. The moment you say "I cannot do it", you already lost.
But DrCyanide explained it way better in his post.