In a word and a half - fucking A.
I've said the other day how I've come across a library of bootlegs and how they're all uploaded in flac format as individual songs. Considering a lot of these are two-disc recordings, and the fact my connection speed is pretty slow, downloading one album takes an insane amount of time. It's a day's waiting around for the files at least.
And of course, as you say, there's no way to tell what the quality's like. Makes me wonder if it's worth it, which is a shame as I've been after recordings of some of the tours I've found for years.