Sometimes, yes. But there are a lot of services where you do need an account to try it at all -- how are you going to try out Mint, or Duolingo, or Path, or OkCupid, without creating an account first?

Obviously you can create "dummy accounts", but they often won't actually give a decent idea of the site's experience (browsing profiles on OkCupid doesn't give you anywhere near the experience of having people message you), and then how is the person going to convert their dummy account into a real one later on, if they never even put in their e-mail or password?

There are certainly plenty of times when sites go overboard in asking too much of you up-front, but it's not always the case.