Validation is easy - you run your site through a validator, and it's either valid or it isn't. The rest of the stuff, such as whether my logo or the biggest headline should be the h1 in my HTML, isn't so easy and is subject to interpretation.
A good designer has technical knowledge - don't treat her like someone who's there to decide whether something should be pink or orange.
Dropbox, with its emphasis on good old-fashioned hierarchies, is superb at automatically saving one original of each photo I take, whether shot with a phone or a fancy camera. No loops, no duplicates, no confusion.