It adds more toxicity than it helps. If you don’t accept the swap they very often troll, afk or soft/hard int.
It is a net negative at least with non-premades. So keep it for premade party members.
If the counter argument is counter picking then we can use the good old logic that the games will statistically balance out, while removing the toxicity from trading.
Since it’s been in the game I’ve had one instance where it causes someone to troll.
It’s one of the best things riot have done for ranked because as much as the community sucks sometimes 80% are human and know it’s a team based game where pick priority means something or can suck it up and carry on as normal if they don’t get counter pick