Sounds suspiciously like not ever needing more than 64KB of RAM.
The reality is that greater horsepower allows for greater abstraction, and easier to program APIs. Increasing developer productivity 2x reduces performance 10-100x, or something like that. So there’s never “enough” performance for the same reason there’s never “enough” powerful/usable APIs.
A current GTX 1080ti is overpowered for a 1080p display, it's too much GPU for too few pixels. If you're driving a 4K display or a head-mounted display with higher refresh rates it will break a sweat, but not on today's games with today's workloads.
Audio used to be really difficult to process in real-time but now it's trivial. There's only so much audio processing you can do before it's ridiculous and pointless.
The same goes for video. Once you have, say, a 40K display for each eye at 244Hz there's no point in going for more pixels or faster refresh rates. If a GPU can handle that, easily, then that GPU will probably be best put to use doing other things in addition to rendering graphics.
Memory is not tied to your senses, we can always find uses for more. Audio and video are, and at some point it's as good as real.
The reality is that greater horsepower allows for greater abstraction, and easier to program APIs. Increasing developer productivity 2x reduces performance 10-100x, or something like that. So there’s never “enough” performance for the same reason there’s never “enough” powerful/usable APIs.