I agree with you on that.

What about * for bold, / for italic and _ for underline?

/ is too commonly used, such as when making a list of replacements/alternatives/synonyms. It works fine when it's just the text as written, but if it was parsing and turned that list to replacementsalternativessynonyms, it would only be getting in the way.

True.

Perhaps //italic text// would be acceptable.

// is common in URIs.

You shouldn't parse '/' in foo/bar/baz or in foo / bar / baz.

If people want to make foo or foo bar italic, they write /foo/ and /foo bar/.

I have no regrets on this one. I thought people would use both, and people do use both.

HN uses *italics*.

I, myself, prefer /italics/, _underline_ and _bold_ in text, if there is no formatting. I feel that these 2 are the least arbitrary, they almost work without agreeing on their meaning beforehand.