[Yads]

Because a lot of the time this is the only game that a casino will spread. They have an interest in protecting the fish and the fish get punished much harder in NL than limit. This is also why a lot of the time buyins are capped at ridiculous amounts.

As for why would a good player play limit over no limit? Usually it's because they are uncomfortable with having their stack at risk on every single hand. Limit also allows you to be in the action much more often, be it drawing, betting, and raising. No limit is a game of waiting for a very profitable opportunity and exploiting it to the fullest extent.