Use? Yes. Back in the day of course it was looked upon as high treason, but nowadays I just don't have the time to solve every puzzle or find every nuance to get the 100/100 score in games. So walkthroughs help. Cheers to the folks that write them for free like the gamefaqs crew (I used to).
I don't glue myself to a walkthrough unless I'm playing the most recent Final Fantasy (because those are known to have important, easily missed items throughout, not just at certain points). But as Yahtzee has mentioned, the developers line of thought is not necessarily your line of thought, nor even the majority's line of thought. And some games are nigh on malicious in their attempts to conceal collectibles.