There's also the simple fact that shipping an identical UI on multiple operating systems is obviously wrong for a least some of those operating systems (and maybe all of them). You don't have to worry about "platform intricacies" because a web-based cross-platform UI toolkit is going to get really basic UI conventions wrong.
It’s not only UI design/conventions being covered, but also things like quirks with the system’s audio, compositor, window manager, etc depending on what your app does and which technologies it uses. If the dev doesn’t understand these things about a platform, they’re walking into a minefield by supporting it.
At this point people are more accustomed to chrome’s conventions than the native UI’s conventions in most cases
But there aren't really many "Chrome conventions" to speak of. Every web app (and Electron app) necessarily has to reinvent a lot of wheels that desktop apps get for free from the underlying OS. And sure, there are component libraries for that... way too many libraries, each of them doing everything slightly differently from others.