In reply to mark k..

You do realize that the decision to drop support for these browsers was precipitated by core discussions regarding goals for replacement editor? And that discussion included one suggestion to use a basic enhanced textfield for listed old browsers, relying on community to produce a plugin if need dictated it? Because I did follow and I participated in that discussion.

Plugin creation based on needs not satisfied in core is a historical fact, and about as old as WordPress. I was speaking to that for features like a replacement editor and others. Sorry if my comment on a blog post wasn't specific enough for you. I'll try and remember to provide links to make.core discussions to provide all the background you clearly were in the dark about. Thanks for your critique.