That is surprising to me, but more pertinently, how often is this the case? Even if expectations don't match, how often do you actually undercut the recruiter's expectations? I would think most people would have a reasonable ballpark idea of what the recruiter has in mind - so just overshoot and then get negotiated down from there. The suggested tactic only really makes sense to me if you frequently expect to be undercutting what the recruiter's got in mind, and even then by a lot.

To my layman understanding, the larger the difference between expectations, the lower the value in this tactic of not revealing your expectations.