I will most definitely expect browser vendors to perform these fixes. I think you've fallen behind on what's taking place in the browser world right now, a huge percentage of users are on evergreen webkit browsers (and increasing rapidly). The next 4-6 years of web will NOT look like the last 4-6 years of web. And this doesn't even account for bundled browser implementations (electron, etc.)
And those evergreen browsers are still doing terrible things when it comes to contentEditable, and they don't really have a lot of choice, because it's an underspecified poorly conceptualized idea that really doesn't leave them much room to things right. There's some work happening on the W3C editing taskforce to improve the concepts involved, but that's also moving at a glacial pace, and having to struggle with browser vendors at every steps.
So again, don't suggest we (editor implementors) are clueless or behind the times. We happen to have spent quite a bit of time on this stuff. We know it.
Again, you are getting offended. Not once did I suggest editor implementors are clueless. They're likely some of the best and sharpest developers out there. Please, as I mentioned earlier, take this project with a grain of salt.
By "fallen behind" I meant still making the assumption that many users are still using outdated browsers. This is not the case anymore, especially in the last year. And because of this fact, many WYSIWYG editors might be implementing a lot of cross-platform bloat that just isn't necessary any more. Rather than raging, perhaps browse through the ProseMirror source and see what you can remove as "obsolete" code.
ProseMirror was started 2 years ago, initially only targeted evergreen browser, and has recently grudgingly added support for IE11 because customers asked for it. But yeah, I guess for some parts of some of the older projects this may apply.
I'd also be optimistic about a future with sane browser WYSIWYG editing, but it has been an uphill battle. I know the W3C Editing task force [0] has been trying to push the limits, but very few successful outcomes so far.
