We do have our sites on functional WP stacks. With enough caching, it's not super hard to make things work (until you hit some edge case with a custom theme/plugin that didn't anticipate a supposedly non-breaking change in the core).

Unfortunately, figuring out why the calendar plugin suddenly isn't producing a functional ical output for windows PCs or figuring out why the s3 offloading plugin has started timing out intermittently becomes a large time investment.

So it's kind of fun to suggest that the people who have the pleasure of servicing WP at a high level are just holding it wrong, but the reality is that there are a lot of talented and experienced people out here working on a platform that fundamentally sucks to work on.

It's not logically inconsistent that, on one hand, people chose it because it's an easy-to-implement solution whose benefit massively outweighs its TCO and, on the other hand, when it break or requires extension it's a pain in the ass for those of us charged with doing that work.