This question has been nagging me for ages.
I've read a lot of Sheldon Brown's site and actually tend to use bikes from the 70s-80s because they're more economical for daily use and especially for a student like me. But I've noticed that some of his opinions can be controversial (his discussion of "lawyer lips"), can fly in the face of industry practices (that all leather saddles, 'properly cared for', are better than any plastic saddle), questionable (that the Peugeot UO-8 makes for the greatest touring bike of all time) and then, sometimes, his opinions seem on a troll level, which I can't think of any examples off the top of my head, but have caught myself falling prey to them. A lot of his material is either very enlightening (his discussion of brake usage) or helpful in that you simply can't find the topic anywhere else on the web.
So the question is, is Sheldon Brown's site really the one-stop for all knowledge pertaining especially to older bicycles, or should he be taken simply as a prolific writer who wrote on a great many topics and should be taken with a large grain of salt? I guess the real question is, how much do bike mechanics especially and others depend on his work, or is it simply a convenient online resource for people new to the sport?