The formatting I do is to ensure:

- Proper rendering of what you're typing on all browsers.
- Proper rendering within idkfa's display constraints.
- Restrictions on what kind of terrible things even the least-skilled hackers could use to insert malicious content into posts.
- Restrictions that people don't overload or fill up the idkfa database with blank spaces or excessive newlines (which won't render correctly in HTML in the first place, even if they are intended).
- What you see as you're typing in the comment box is as close as possible to what the post will look like when you're previewing the post or after you're submitting it.

I like to err on the side of caution rather than have the ability to display ASCII art.