It very much depends on the games made and who they are trying to sell to.
Not all games are a fit for all consoles, even the 3rd party ones, porting to all platforms costs money, like buying 3+ platforms to play on and some smaller Devs can't do that and have to stick to 1 or 2 platforms, in which case, exclusives may come because the game they are making has a better chance of success on 1 platform over another that may not make the money back to cover the costs of a port