Right. Here's a map of FCS teams...it's a bit out of date (from 2011), but still shows the relevant information for this discussion:
Take a look at the stretch of Michigan, Wisconsin, and Minnesota.
Michigan - population ~10M, zero FCS schools, although 5 FBS schools (including a couple that really probably should be FCS)
Wisconsin - population ~5.8M, zero FCS schools, 1 FBS school
Minnesota - population ~5.6M, zero FCS schools, 1 FBS school
To "generalize" a somewhat familiar rating system:
5 star kids - they can go anywhere they want
4 star kids - many will be going to the big state schools...Michigan, Mich State, Wisconsin, Minnesota
3 star kids - many (especially the kids further east in this region) go to MAC schools...ones in the west might go to Wyoming, NDSU, maybe other Mountain West schools
2 star kids - many of these kids are going to MVFC schools...NDSU, SDSU, USD, UNI in the west, but in the east...YSU, INSU, ILSU?
1 star kids - maybe to nearby Pioneer League schools or to fill in depth or PWOs at MVFC schools
So, you have a big area with lots of kids and a few large-sized metro areas (Detroit, Minneapolis, Milwaukee). You also have a significant lack of schools in the scholarship FCS level. Lots of kids who are good enough to get a D1 scholarship, but aren't quite good enough to (or just don't want to) play on a MAC team. If they want to stay within a day's drive of home (so parents can attend games, so it's not horribly difficult to go home every now and then, etc.), then they don't have a lot of options. It's a good idea to focus on these "underserved" areas to try to get some good kids that might get missed.
Another bonus is that a kid who's grown up playing football in the fall/early winter in MI, WI, or MN...they're not going to flinch at playing football in central IL in the same timeframe. If anything, the weather might be a little warmer (and for kids from MI...with a bit less snow probably).
Obviously there's other regions we like to focus on...we've had a lot of success getting kids from the KC area...kinda for a similar reason probably...but if not a lot of your direct competitors are recruiting in an area and there's a good number of quality kids in the area, it makes sense to put some focus there.
EDIT - one more point...assuming kids are more likely to stay within a state or two of home, kids from the previously mentioned states have fewer options since going north would mean Canada, where the options to play gridiron football are much more limited, and probably would involve a few more "hoops" to jump through.
EDIT 2 - more stuff...
I was added in the new offers to the spreadsheet and noticed that a lot of them have quite a few MAC offers already and some even higher. Like, for example, here's the list of offers Trebron Mosley currently has: Purdue, Morgan State, Michigan State, Eastern Michigan, Michigan, Boston College, Minnesota, Iowa State, Northern Illinois, Indiana, Ball State, Bowling Green, Toledo, Western Michigan, Syracuse, Cincinnati, Central Michigan. So...there's no way we're beating out that list for this kid. There's 5 Big 10 schools on that list. What we're likely doing in this case is, say the kid gets to Michigan, or wherever he goes, but things just don't work out for some reason. Maybe grades...maybe lack of playing time...whatever...but after a year or so he chooses to transfer to an FCS school where he can be a starter. Well, we are now on this kid's radar if that happens. He starts thinking of places to transfer to and he's probably going to start with the schools that showed interest in him in the first place.
This is essentially an investment in the future (that doesn't really cost us anything).