And also the recruiting vacuum that is left after FSU and Alabama deplete the 4 and 5 star HS recruits.
There is no recruiting vacuum. There are plenty enough recruits to go spread among the major programs. Plus a ton of less heralded guys that will break out all over the nation, at both major programs with a championship history and the likes of Vanderbilt.
While no doubt it helps to win head to head battles against other programs for the most highly recruited and highly publicized players in the nation, nabbing 5 star recruits doesn't guarantee anything. At all. There are plenty of programs out there that have picked up "top 5" class after "top 5" class, year after year, and have nothing to show for it. There are plenty of examples of programs that ended up with classes that recruiting services ranked very low, only to turn out to be some of the strongest in the nation.
That's because it all comes down to how good a particular coach is at evaluating and developing talent.
Also, recruiting services tend to give anybody Bama recruits a fairly significant bump. It was ridiculous what some of these services did to Urban Meyer's classes when he was back at Florida.
It's because most of the people who run these services know absolutely jack shit about high school football, or football in general. The staff at these websites boost the rankings of players who go to play under coaches like Nick Saban or Urban Meyer because they know that these guys are some of the best in the business at what they do, and that if they move these kids up, they will look good later when people are reviewing just how accurate their rankings were that year.
They look at which schools and coaches are recruiting a player, how many scholarship offers a kid has and which schools are offering, all sorts of combine numbers which tend to be wildly inaccurate, and maybe a 5 minute highlight tape if they are up to it.
Basically, the ability to win head to head battles in recruiting is important, but the rankings posted on recruiting services do not nearly approximate the rankings of these athletes given to them by college coaches. And even those aren't very likely to nearly approximate reality.