Yeah but try pressing more than 4 keys at once on the PS2 keyboard and get back to me

That is a limitation of the keyboard not the PS/2. Unlike USB which is limited to 10 simultaneous key presses, PS/2 supports full n-key rollover.

This, it’s why I still use the PS2 interface. Full n-key rollover is impossible for me to do without.

Out of curiosity, what is the practical use of full N-key rollover? I can’t think of many things that require me to press more than maybe five keys at a time.