That seems like overkill.
It is, and I don't like it any more than you do. However, it's often the most expedient solution, given the limitations of remote troubleshooting imposed by this or any other back-and-forth kind of discussion. It's also completely nondestructive of your User account information or data, so it's harmless.
It might not work anyway.
To be clear, I'm more curious about what could be causing this than actually anxious to find a solution.
So am I. It's not something I have ever experienced or even heard of before. If you were to reinstall macOS the problem will either be resolved, meaning you'll never know what caused it, or it will persist, and you still won't know. Most people on this site just want to fix their Macs and I appreciate your curiosity.
Did you try deleting these files?
~/Library/Preferences/com.apple.TextEdit.plist
~/Library/Containers/com.apple.TextEdit/Data/Library/Preferences/com.apple.TextEdit.plist
If you use iCloud to store your TextEdit documents, the following is also applicable:
~/Library/Application Support/CloudDocs/session/containers/com.apple.TextEdit
If it doesn't help I may have additional suggestions.
(Pathnames edited to mitigate word-wrap problems with this site)
Oh and one more thing: if you were to create a new, temporary User Account, and the problem is not duplicated in that Account, you will have definitively isolated it to your User space. That would help advance troubleshooting. To learn how to do that read How to test an issue in another user account on your Mac. When you are finished troubleshooting, you can remove the temporary User Account by following these instructions: macOS Sierra: Delete a user or group. Before removing it, confirm you don't need any of the files you might have created in that Account.