because they don't want to learn his new playstyle
Did it ever occur to you that this could be due to it not being satisfying, enjoyable, or rewarding?
I'll admit, a lot of people don't want to learn his playstyle. Having actually learned it myself, even back when it was massively over tuned, i can understand why people wouldn't waste their time learning it. The reworked malzahar isn't fun, reliable, or compelling.
There is very little difference between having learned the kit and not having learned the kit, because so much of it is subject to internal mechanics which pigeonhole you into a specific casting pattern, and all kill potential being placed onto his W, which is a inconsistent garbage ability, which functions without any player interaction.
(Seriously the difference between a poke play and kill attempt, is pressing W at some point during the exchange)
If you are using the rest of your kit in the one specific "acceptable" play pattern, then your W is basically automatic. You have basically no control over it dealing 0 or 2k damage, and considering it's the only part of your kit which offers reasonable kill potential, it makes the champion feel completely unrewarding to play. If you can't kill anyone, it's because the kit failed on it's own. If you kill everyone, it has nothing to do with you, it's all due to them not killing the voidlings and all you did was press W. It required no aiming, no timing, no micromanaging, nothing. It's just shallow boring gameplay that has a very low skill floor and an equally low skill ceiling. Which riot seemed to think was the case with pre-rework malzahar, which is probably one of the most ignorant or disingenuous beliefs riot seemed to hold about malzahar during the rework process.