Are NTSC and PAL affecting display rate
Not only do the two TV systems run at a different frequency, but the difference in frequency also dictates a difference in frame size.  PAL is 625 lines, whereas NTSC is 525 lines.  That means that games (and the consoles) have to account for that difference in size in their graphics and playfields.

And then, on top of that, the two systems both use a different colour coding scheme1.  The hardware in the console has to be able to do the right colour encoding to be able to display on the right kind of screen.  You can't just plug a PAL console into an NTSC screen and expect it to have a clue what is going on - the same the other way around.

Most games consoles tied the action to the video output frequency.  Frames were calculated and drawn at the same frequency as the screen, so the gameplay was often quicker on an NTCS console than on a PAL console.  The internals of the console had to account for that change in speed, and so they would usually have a different core clock (and different crystal value) for NTCS devices as compared to PAL devices.

So you see, the TV standard the console is designed to work with affects a lot more than just the frequency of the TV signal.



1 NTSC used to be known as "Never The Same Colour" as the colour coding system used in it was quite poor by comparison to PAL.  You could never quite trust how the colours would be represented from one device or broadcast to the next.