I have the idea that no pianist can play everything equally well.
I agree, every artist has their strong points and weak points. But the greatest artists are good at everything. The fact that they are great artists means they can pick and choose what they want to play, so they gravitate towards what they like, which is usually their strong points. They didn't get to be great artists by putting their bad foot forward.

I was trying to think of someone who could and can't.
I guess it's going to come down to subjectivity.
I can't, and it usually does. We all like what we like.
Examples-
Argerich and Richter playing Mozart don't go for me.
I enjoy both of them in Mozart, although it isn't what we've been taught to expect from a "correct" (what's that?) Mozart interpretation. Richter's Mozart d minor Concerto is my favorite recording of that work and Martha's K.576 is masterful, as is her (not Mozart but close) Beethoven 1st Concerto.
But if I had the chance to see either of them in a Concerto I would want to hear them in Prokofiev or Rachmaninov, hear the full range of their playing and hear them; well, really tear it up.

I heard Andre Watts play Beethoven 1, and it was REALLY great but I kept thinking "I wish he was playing Totentanz".
Can't imagine Brendel playing Messaien
I can and don't care to

Perahia playing Prokofiev
I heard him play the Bartok Suite Op.14 and it was great. Don't know why he doesn't play more 20th Century lit. I suspect his managers and record producers guided him away from it, or that he felt more simpatico with Mozart, Schumann and Chopin. And because he's Perhaia, the choice was his to make.
Horowitz...well, I don't really like Horowitz so...

It's subjective as I said
Indeed it is.
