It's missing support for the way you used to get boldface on a typewriter: Type a word, then go back and type it again.

This is why the source of manpages does boldface (and underlining) like that -- it's from the days of lineprinter terminals!

For example, to write "hi" in bold, a manpage's source does this: h^Hhi^Hi .. and to underline it: h^H_i^H_

Also, if you keep typing off the end of the page, it doesn't simulate what would usually happen on a real typewriter: you'd get ink on the roller.