Anecdotally, my experience isn't like this at all. I'm pretty good, maybe even better than average, at talking to people in one-to-one conversations, at home, at cafes, on the bus, before class, and pretty much any time other than at deliberately social events. But at bars or parties, the constantly shifting conversations of dozens of people trying to all talk to each other at once at a mile a minute, about nothing in particular, in a loud and overstimulating environment completely discombobulates me, and I usually end up either ignored, unable to break into a conversation more than once every few minutes, or just plain bored with having nothing to say but the same small talk everyone else is making.

In my case, it's mostly the other way round. I enjoy talking to groups of people and even entertaining them, but in one-to-one conversations I quickly lose interest or run out of things to say unless the other person is someone I particularly like or we have interests in common (such people comprising maybe 30% of the population or less).