It's not just the save dialog, I mentioned the file selection dialog (for uploading) in the post. The Librewolf "save page as" is just one singular example, not the entire problem!
"Saving HTML files with their file extension" can still be accomplished if I can see all the files at once. I'm not changing the extension, I just want to see where I'm putting them. There is no reason why viewing all files would prevent me from saving the same file types together.

