Great approach fredck and glad you brought it up!
In short, there are lot of things that I expect from a text editor which contribute to quality content. It’s about guiding what the writer should be able to do. Essentially, the reader must be understood.
Just to mention three examples:
#1 As a reader you don’t like distractions. To create a main distraction just use different typefaces through your piece of content and you’re done. Most text editors out there allow to select a different typeface for every single letter. By the way, another nice distraction are creatively misaligned images.
#2 Consuming contents with a hard to follow structure is frustrating. The reader leaves without willing or being able to understand the message. Every text editor supports headlines that can be mixed all the way. Shouldn’t a H1 be followed by a H2 and not H5 just because the writer wanted a nice and smaller subheading?
#3 It’s very likely that the writer burns for the things they are writing about. But as a reader you don’t know what to expect from a story which is 47 meters long. So, reading a long story might always be a risk of wasting time. If there was a summary at the beginning, the reader could choose if to dig deeper. At first sight this might not belong to what a text editor should support, but I think it would change the world for the better if the text editor at least prompts.
A good text editor should not supported features just because they are technically doable. Above everything it should consider the reader. And you are on a good way of finding out. Good luck!