[jfindley]

If you only use your computer for web browsing, then sure.

But the consumer market is more than just this. Several popular "consumer" applications, such as gaming and photo/video editing, continue to see benefit from increases in CPU performance, and single-core performance (what most people actually want when they ask for higher clock speeds), continues to be very relevant to this day. Not all workloads are easily parallelizable.

[chriswarbo]

Work grows to fill the available time. "IT" style tasks, like reading/writing documents, spreadsheets, emails, etc. don't require anything like the resources they currently use, or those they used in 2000. They use(d) those resources since there was no reason not to.

Lots of (most?) software development typically charges ahead without much regard to resource usage, until performance becomes a problem; then things are optimised until performance is no longer a problem, and the charge resumes. This results in software with performance which is just about acceptable, regardless of what resources are available. It was the case in 2000, it is the case now, and it would be the case if we had 50GHz machines.

This is the case for tasks where the main bottleneck is 'has anybody bothered to implement this yet?'; I'd say your examples of gaming and video editing are tasks where performance is a major part of the bottleneck. Arguably, Trello didn't exist in the 90s because nobody had bothered to make it yet; Skyrim didn't exist in the 90s because the machines weren't up to it.