Some people seem to forget that all the Doctors are the same person.
I know, sometimes I end up thinking about them a bit separately, and classifying certain things as exclusive to a particular Doctor in my mind. But there are people who really take this seriously.
I once saw someone criticizing the 13th Doctor for looking like the 11th Doctor. Wow, how strange for someone to act so similar to themselves, how shocking.
Of course, it was more directed at the actors, but honestly, how can anyone not consider this a good thing? It shows that the actor watched the series and considered it the same character. This is literally necessary.
I think they do this worse with Jodie Whittaker, I think because she's more different from the 12th physically. But a lot of people seem to forget that the 14th and 15th came about because the 13th lived; that counts for character development.
13th acts the way she does because of what happened during 12th's era. That's why she's more distrustful of the Master (because Missy and the Master abandoned her) and because she's more distant from her friends (she lost Clara and Bill), which is why she babysits her companions.
Another example is how difficult it is for people to connect 12th's problems with 11th's actions. 12th is literally a remorseful guy trying to start over because he realized he was becoming a soldier again.
The series, even though you can skip Doctors, has continuity.
We (as a fandom) separate the incarnations too much, and this is sometimes the result. Talking about 9th and 10th as separate people leads us to think of them as separate people. It's important to remember that they're not different people who just happen to have the same memory.
