Perhaps it is because the last 20 years has seen a shift in developer culture away from lower-level understanding and native applications so that all the vibe-coded apps you use on the desktop are Chromium-based web "applications".

If you apply AI to low-level applications, it is quite good and you avoid the runtime bottleneck of webness, I have found. Eg. https://github.com/Redrum624/Vitrine is very good but has a horrible UI due to the webby nature of its rendering - all vibe coded. If you used a native toolkit it'd feel completely different.