Close your eyes - not if you're driving! - and picture a Facebook game. What do you see? A farm, most likely, or perhaps a city block or even the inside of a fifties diner. (If you see Triple Town, of course, you get a free biscuit and a chummy punch on the shoulder.)
There's definitely an increasing number of good games on Facebook, but many of the things you'll encounter offer little but charmless toil: plant this, scrub that, build this, tell your friends. Could I have some money now? Could you tell your friends I'd like some money, too? It's like having a tapeworm that lives in your gut and eats five-pound notes. Occasionally, it will poke its head out and have a quick round of Ludo with you. Like!
PopCap's approach has always been a little different. PopCap's games all have monetisation, of course, and, yes, they do work a touch better if you enjoy them alongside your friends, but they're not about clicking and waiting, planting and tilling.