You're both losing sight of the original point - that is, Wolf Kanno is wrong about what customisation means. I'll just interject here with some proofs against his assertions.

Assume that once the option to learn a spell is available, all characters will be able to learn it instantly by grinding or so (this is unrealistic, yes, and incredibly so in 7's case). In 6, that means every character has every spell learnt and available at all times, no penalty, whenever you receive an esper that can teach that spell. In 7, however, this means you're actually FORCED to make ability decisions as early as you get Tifa (whose max ~2 materia slots at that point mean you're dropping half of Ice/Bolt/Fire/Cure).

Additionally, Master Materias simply grant access to all the stated abilities - they have limited/poor connectivity to support materias. The grind to get master materias is a lot more punishing, too.

There's definitely a point to be made about not teaching your dudes magic so that the RNG in the Colosseum has less actions to choose from, but really, that's just compensating for poor game design.
Quote Originally Posted by Wolf Kanno View Post
The other issue with VII's customization is that the game suffers from the same Achilles heel of VI and well most of the FFs have, which is that the game isn't difficult enough to warrant a complex strategy for the customization system it gives you.
This is mostly true, except for the fact that 7 gives you 2 enemies where your materia setup will actually matter, no matter how much grinding you've done.

For example: