Is this a pattern?
I began to wonder after having read this exchange in AlmostFreeText:
Could it be that real men do underline -- just not in printed text. I know that I find handwriting italic/bold quite hard. Sometimes I use italic on whiteboard class diagrams, but generally I prefer to underline.
In situations where there are URLs not, I underline as much as the best of 'em; on the web, I might underline very very rarely, perhaps *say* the section title in a tech_doc ... but even then, only maybe. Underline is for links. --BenTremblay
Book titles, foreign words, etc. are italicised in typeset print.
Because handwriting italics is difficult, and making a typewriter do italics was impossible, authors underline words they want the typesetter to make italic.
It's like the two kinds of the lowercase "g" -- one kind just has a tail at the bottom, the other kind has a little loop. But the difference is irrelevant. They both mean the same thing. Switching back and forth in one piece of text annoys the readers.
-- DavidCary
Many people merely "browse" email messages due to limited time, laziness, etc. Thus, it's sometimes useful to underline key points so they can get the gist of the key issues without reading the whole thing.
That's what strong is for.