needing to type html-tags with a mobile would be a no-go

It's a pain and one that should be un-necessary. If the code that parsed the input assumed that everything without any markup was actually meant to be in <p>paragraph</p> tags, that alone would make posting and commenting on mobile much easier.

The parser already checks for missing tags so it is not too much of a stretch for it to be able to guess which ones need adding. Perhaps with more rigorous enforcing that the contributor checks with the preview.