drhowarddrfine - 8:07 pm on May 25, 2013 (gmt 0)
I agree, and will go further. It's more than just a rule, it's a fact. This has less to do with style than it does with the practical and utilitarian concern of making content easy to read.
And it's no longer true as I said earlier.
There was a whole collection of articles I read a couple years ago by Andy Rutledge, iA and other designers, and especially a list of other real type and font designers who finally turned the tide at my company and made us believe what we were afraid to say out loud. That you use serif or sans-serif that is legible in the font and size you want to use. You NEVER use sans-serif, or avoid serif, just because it's on the screen or the web.
I wish I kept the collection of links, having only deleted them a few weeks ago, but I'm not sure I could list them here anyway.