I don't understand most people.
Quite a lot want to play nice
freerolls, and CC freerolls are amongst the best looking at the prizepool and the average number of players.
I'm not 100 % sure at how many sites CC runs their freerolls, but I think it's 7 rooms.
So, reason 1 to open more accounts, sticking to 1 or 2 rooms means missing out on a lot of good freerolls.
Reason 2, as most people want free money, sticking to 1 or 2 rooms means missing a lot of promotions like new-player freerolls, free tournament tickets etc...
Reason 3....more rooms, more traffic and so more chance to find something you want to play.
Reason 4....more rooms means more weaker players.
You might fall in love with Pokerstars, but competition is relatively strong there.
There's plenty of rooms where players are just utterly weak.
Weaker players means more money to gain.
So, I'd say, for the real recreational player, just playing for fun every now and than, sticking to 1 or 2 rooms is a good option.
Taking it a bit more serious, you're a thief of your own sticking to just 1 or 2 rooms.