Recruiting rankings don't matter, but getting top recruits does.
You are exactly correct. But the thing about recruiting rankings, the way they rate a kid is as much influenced by the schools recruiting them as it is by the kid's talent. In other words, it doesn't matter if a kid is pretty good or too stupid to tie his own shoes, if Texas and Oklahoma are fighting for the kid, he is going to be rated a 4 star recruit. Likewise, a kid with 4 star talent, if he grows up in backwater, can be a fan of a smaller school, commit there early, not send tapes out, and he'll be either unranked or given 2 stars.
The magazines don't care, or at least only care as it relates to sales, because ranking Texas, USC, LSU, Oklahoma, Alabama, and Florida with the top recruiting classes every year is close enough to look like they know what they are doing. Plus, it sells the most magazines possible without having to do a lot of real work, because those are the teams with the biggest fan bases.
Meanwhile, a team like Boise St, who has never had a class ranked in the top 50, continues to make them look like total jackasses to anyone who pays attention. I mean, how can a team go 35-4 over the last 3 years, including a BCS bowl win, without a class in the top 50??
Sorry, didn't mean to go on a rant there, but the importance some people place on recruiting rankings is #3 on the list of things I just don't understand.