Sure, but think about the past thirty years of web browser development. Every time software developers make a faster browser with cool new features, content developers make content that uses all that new capability. It's sort of the content equivalent of Wirth's Law (software is getting slower more rapidly than hardware is becoming faster.)

Developers almost always have reasonably beefy hardware setups (because the software they use requires plenty of memory or compute resources.) Does the OP's observation imply there's a wider range of hardware out there? Maybe people constructing the pages they're complaining about assume everyone will be on a kick-ass machine with the best GPU money can buy and on a low-latency / high-bandwidth network. Maybe it's an observation that too many web developers don't consider consumers with more mundane circumstances.

Also... I use Lynx and EWW a lot. The web seems pretty zippy when you're ignoring the images and javascript. But yeah, that's not a general solution, too many sites require javascript to function.