Netflix has plenty of Adult Animation though. They just don't have anything done in the style of a 20th Century Animated show which is what you are talking about with Bob's Burgers/Central Park (both 20th Century properties). Speaking of Central Park though, I expect Apple TV+ to run that as long as they can justify it because once they cancel it, it goes back to Disney after a set number of years and they'll lose all rights to it.
On the sitcom front, i've said for awhile they should try to create their own sitcoms so that they don't need to keep licensing shows, but they are very good at finding great shows that American audiences aren't too familiar with and making them big such as Canadian sitcoms like Schitt's Creek or Kim's Convenience.
Netflix is doing a second spinoff of That 70's Show called That 90's show with the original cast coming back, but the thing is, they aren't the production company on the show, so they'll eventually lose this show from their service over time, much like they lost the Netflix Marvel shows and will soon be losing all five seasons of Arrested Development to Disney.