Being the one (or two) solos in a premade really sucks
Not really sure why I don't see this point made more often, but even in games that are 3/4 man premades vs 3/4 man premades, there is always one or two solo players, and it really sucks to be stuck in that team. Most of the time they don't communicate in chat, refuse to ping, and are so busy camping their buddies lane that they have no time for you. Also, one of their lot can go 0/4/0 and be just fine, but you 4/4/4 and you're complete shit and the reason the team is losing.
Maybe it's just me, but I hate playing with OR against premades.