Yeah, but HTML rendering is not Edge's problem.
It's the UI and user features like user data management, password management, etc.
Edge is a perfectly servicable HTML renderer wrapped in a painfully barebones user experience.
I have every expectation that Anaheim will be the same.
(The same problem extends to basically all the modern apps. What they do isn't the problem, the problem is that they have such low manageability that when something goes wrong there are few to no options to fix it other than "nuke it and start again", and for the longest time you had to use Powershell to do that
This is all a legacy of how Windows 8 and these new modern apps were designed in a tablet oriented fashion, and tablet oriented design largely assumes that data is being accessed/mirrored from an online source rather than stored locally, which is more commonly the case on a desktop OS).