Comment by mmooss

Also, different languages have different formatting varieties. 256 combinations doesn't seem like nearly enough.

Note that is 256 combinations. If you want both bold and italics, either it's one of the 256 combinations, separate from the bold-only combination and from the italics-only combination, or you need another 8 bits for each option.

I think HN made a very aesthetically pleasing decision to exclude bold and underline. Imagine the appearance of comment pages if those were options.