casual doesn't just mean easy, it's a whole different vibe
there are people who play to have fun and there are people who play to win, while the two are not mutually exclusive I'm not quite sure how people are oblivious to this divide
if I queue a game with no care to win and just want to screw around with the heros and items (which I do frequently) there really should be a queue for that because the type of person that plays to win is probably not going to have fun in the same lobby.. the same goes the opposite direction as well.
when we had a dedicated ranked queue there was a lot more space to screw around in casual which I really enjoyed, I'd sweat my ass off in ranked for 2 or 3 games and then go do something silly in casual after running out of steam
also longer format games (league) are generally much more friendly to off-meta builds, having more time to farm and scale gives off-meta builds an opportunity to 'come online'.. not to mention league is frankly less of a team game than deadlock so it's not particularly hard to carry someone using an only semi-viable build.... maybe if you played a region with ranked you'd understand the points I'm making ;p
-diamond 2 peak, soloq support only