One reason is that for a very long time, if you created a native WebView on Windows, you would get an IE7-compatible browser, even if the user had installed a much newer version of IE. There were a couple of tricks you could use to get the user's actual browser version, which I described some time ago here:
In any case you were still dependent on IE10/11 at the best, and certainly nothing as modern as the old Edge, much less the Chromium-based Edge. And on older Windows versions it completely depended on whether the user had upgraded IE.
You could write HTML/CSS/JS that was portable between IE10/11 and other native browsers, just as we all did in actual websites. I did this for Mac/Windows in the past and it worked, but it was fairly compelling for web developers to have a single browser version to target instead of the various incompatible native web views.
The situation is a bit different now, where you can get an Chromium Edge view on Windows 10 and a Safari view on Mac, but what do you get on Linux? I don't know.
http://forums.apricitysoftware.com/t/why-is-markdownpad-spaw...
In any case you were still dependent on IE10/11 at the best, and certainly nothing as modern as the old Edge, much less the Chromium-based Edge. And on older Windows versions it completely depended on whether the user had upgraded IE.
You could write HTML/CSS/JS that was portable between IE10/11 and other native browsers, just as we all did in actual websites. I did this for Mac/Windows in the past and it worked, but it was fairly compelling for web developers to have a single browser version to target instead of the various incompatible native web views.
The situation is a bit different now, where you can get an Chromium Edge view on Windows 10 and a Safari view on Mac, but what do you get on Linux? I don't know.