I think the answer is much simpler than yoji's - FSS is simply wiped clean at the start of each season (after recruiting ends).
It'd get kind of tricky holding onto all of that data - you'd basically have to create a new page that lists all players that you have FSS for since the only real filter they have on that currently is to filter by scouted states, not scouted players. Plus they'd have to account for things like "I recruited this player, he went to a different school then transfered, so I should have his FSS now". Which means, from a data end, you'd have to link FSS to specific players rather than the states they are located in (as I'm guessing it is done now on the WIS backend).
It'd basically have to track your FSS over a few seasons rather than just last season, so it'd get complicated and data-heavy... two things WIS tends to shy away from in updates, especially the latter.