Python is not good for CP since it is slow.
It also has good support for very large numbers which encourages people to solve certain arithmetic related problems in the wrong way (you get TLE).
Python gives less control over the system memory it consumes (unlike c/cpp), a side-metric on which CP performance is measured.
Probably you don't use python then. Every Judge has a 5x multiplier for python. And yes you can also control the memory in python. Don't discourage people for using python.
Another main reason I think is that it has so much stuff built-in that when a newbie programmer learns python he doesn't need to understand concepts like how variables are stored in memory, which is important to understand in the case of languages like C/C++, now it may look like an advantage but all it does is makes us ignorant to the stuff which happens "under the hood". I don't think it has really to do with CP specifically, since many people learn C/C++/Java as their first language and hence use them for CP.
Did you know that you get more time in competitions if you use pyhton.
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