Every order of magnitude of difference constitutes a categorical difference.
The ability to create spam instantly, fitted perfectly to any situation, and doing that 24/7, everywhere, is very different from before. Before, spam was annoying but generally different enough to tell apart. It was also (in general) never too much as to make an entire platform useless.
With AI, the entire internet IS spam. No matter what you google or look at, there's a very high chance it's AI spam. The internet is super duper extra dead.
But none of these are unlimited, that was never the expectation. It's a flat rate for a flat (but hidden) amount of usage. What's disgusting is that they want the good parts of subs (low usage subs), but then just ban the bad parts (high usage people). I don't care whether that's technically possible, it's incredibly scummy.