If the only thing being removed were tags, which don't have structural or semantic meaning, it would probably be just as easy to parse for screen readers and robots.
Two problems I see:
1. Where you have a heading you may want it and its associated content wrapped in a . Where you have a separated paragraph you really do probably want a
.
So these newlines aren't always just replacing s. The page has no structure except what can be derived from headings.
2. Wrapping everything in a tag seems like it could cause issues. It would probably be better to use and apply the clever one line of CSS mentioned in the post.