Do you believe new releases don't introduce new bugs?

Obviously. Every release introduces bugs. There's an inevitable positive correlation between the amount of code we write and the number of bugs we introduce, we just try to minimize it.

The probability of introducing bugs is a function of the amount of development being done. Releasing less often doesn't change that. In fact, under that assumption, delaying releases strictly increases the amount of time users are affected by the average bug.

People who do this tell themselves the extra time allows them to catch more bugs. But in my experience that's a bedtime story, most bugs aren't noticed until after deployment anyway.

That's completely orthogonal to slowly rolling out changes, btw.