Batman debuted on May 1939, Robin debuted on April 1940, 11 issues after Batman, and not even a year after the latter's debut.

Robin debuted before, and not limited to: Joker, Catwoman, Scarecrow, Penguin, Two-Face, Riddler, Mad Hatter, Clayface, Mr Freeze, Poison Ivy, Alfred, Leslie Thompkins, Lucius Fox, Vicki Vale, Wayne Enterprises, the Batcave, the Bat-Signal, heck, Robin debuted before Gotham City was even CALLED Gotham.

There are precisely 6 elements from the Batman mythos that still remains to this day that debuted before Robin: Batman himself, his origin story, Commissioner Gordon, Hugo Strange, the Batmobile and Wayne Manor.

But despite all of this, it's a persistent claim among casuals that "Batman works alone" and that "Batman should go back to being a solo crimefighter".

Why is that?