Haven't forfeits always been a part of wrestling? I have no clue on the overall trend or anything like that, but it doesn't seem to me that it is horrendously worse now than it was when I wrestled, or when I began coaching. All of this stuff ebbs and flows too. This will be my 11th year as a head coach, and I can say that in the last decade alone I have seen teams that had literally 3 wrestlers on the team at one point, go on to be at team state, and win regionals. I have also seen it go the other way, teams with a lot of kids go down to a few.
I think A LOT of it is about the "culture" of the sport at the school. For whatever reason it seems like some schools have it, others don't. Again this can change with a class, or with various coaches...
I also don't see this as an issue that is small school vs big school. I spent my first 9 years at a small school, and we very rarely forfeited, not that it never happened, but it seemed easier to get a kid to try it out, or come out to fill a spot. I now coach at a much larger school, and had two forfeits all year. I've found communication to be much more difficult at a larger school, and I am in the building. I imagine that getting things "going" is much more difficult no matter the school if your not in the building.
With this being said once a team culture is established with-in a program it is something that can last for a long period of time. It is just difficult to get going. I would also say in my opinion getting the culture right is just as important to a program as having a coach who knows all of the moves in the world.