Kane & Son are world class. He never had those type of players at United. He can’t develop young players so he bought Sanchez, Lukaku & Pogba but two of them aren’t world class and the other one in decline deadwood.
In my opinion, Mourinho needs 4 world class players & experienced defense in order to win title. It’s similar to his inter when he had Milito, Eto’o, Sneijder, Cambiasso & experienced defenders.
He might have his own Eto’o & Milito at Spurs but he doesn’t have Sneijder & Cambiasso in his midfield. That is where their limit is to prevent them winning the league with the current squad.
In fact, in United forum, a poster posted xG graphs of United vs WBA and WBA vs spurs. Both United & spurs won the game 1-0 but United has so much higher xG than spurs which tells you their midfield don’t really create high quality chances but Kane & Son are just being more clinical in converting those low xG chances.