"Point and click" is a generic term that can be universally applied to every champion, game, and interactive action within the world of computers. Bad choice of words.
Which support are you referring to that has brain-dead mechanics? Lulu, Janna, Braum, Thresh, Blitz, Brand, Leona Ziggs, Vel Koz, Nami, Zilean, Soraka, Rakan etc. use mechanics when laning in a multitude of skill shots and positioning.
Had you said "Anyone auto-filled into a role they are unfamiliar with, the game is lost.", you would be correct, but you ruined your argument with flawed reasoning. Of course a support main will do poorly in top lane, because they don't know the matchups or play style; that can be said about anyone filled in a role they don't regularly play. Supporting is harder than people give it credit for, there's much more awareness and decision making that comes into play once laning phase is done.