Because what Chelsea did was create two barriers in front of the goal. This makes it difficult for any team to score a goal. For me, Tuchel only tried to defend and eventually try to counterattack.
I think Chelsea had the ability to do more, but they just didn't create almost any danger for Man City. If Chelsea couldn't do it, how are other clubs going to do it? Of course there may be suppressions, but at this point they will be difficult.
I think that Liverpool are stronger than Chelsea this season, so it shouldn't be seen as the only club that can take on City in the Premier League. Moreover, after the defeat, Chelsea let up Liverpool at the second place, and Liverpool played one game less than Chelsea. In any case, the only thing left for Chelsea is to fight for second place with Liverpool, maybe Tottenham will try to join these teams, but as we saw in the cup matches, Chelsea confidently beat Tottenham.