Didn't Mount get voted players´ player of the year twice, including the CL winning year, by his Chelsea mates, and featured regularly on the England side? How does one gets so far with poor general play?
Because football is a team sport, and he was carried by much better players. Same reason people used to argue with me about why Donny was a bad signing with people using the "he was the 10 for a good Ajax side who lit up Europe so surely he's a good footballer".
If you actually watch their games, it is clear that they benefit greatly from having midfielders like Kovacic (for Mount) or de Jong (for Donny) carry the midfield with their press resistance.
That's what separates Mount and Maddison apart. Mount is very weak and poor under pressure whereas Maddison is press resistant.