> Web applications are not inherently more (or less) stable than native applications

Absolutely. The browsers are extremely stable and generally don't crash. The individual applications may still be bug prone but those bugs generally don't take down the system.

> OS compatibility issues were replaced with browser compatibility issues

Sure, but it's a much less severe problem (the potential for bugs rather than binary incompatibility) and one that developers can easily remedy based on visitor statistics without customer's having to download, update or take any action. This problem also becomes much less of a problem every day as the browsers converge on common standards.

> This problem also becomes much less of a problem every day as the browsers converge on common standards.

Only Firefox and Chromium are able to keep up. It's an improvement over native apps working only on Mac OS and Windows as they are mostly open source, but still only two platforms.

It doesn't matter because when a webapp crashes, it doesn't bring down your whole machine (or these days, even your whole browser).

The killer feature is effective per-app sandboxing.

What? Native apps crashes stopped bringing down the machine decades ago. Sure there's the occasional bug in the OS (= kernel and system services), but browsers have bugs too.