I think there's more pressure in team games with people "shouting" at you for every mistake you make.
Well, true, but if you learn the game from 4v4, 2v2 and then 1v1, you won't be total noob.
If you learn the game from 1v1 you will end with 200 1v1 and more defeats than wins. It's not encouraging.
I'm talking from my point of view. Ive started from 4v4, moved to 2v2 and now 1v1. Despite I don't have many 1v1s, Im beating players who has a way lower level than me and many, many, many more 1v1s. Why? Because I was not learning basic things from 1v1 and I entered 1v1 with some experience.
And like I said, getting -20 streak in 1v1 is really discouraging.