I don't disagree with you coach. I am currently at Ritter and there are a couple of reasons for the lack of numbers. The two biggest are numbers at the youth level and support by other coaches.
For the youth level, the CYO is dying a slow, painful death in wrestling. We have tried to bolster the teams as much as possible in the last 3 years, but we have only added about 15% in numbers to our teams. It is near impossible for me to get into other feeder grade schools and get the kids to come out and try the sport. Kids just don't seem to be tough enough to try the sport in high school and stick it out. The numbers for attrition are much higher for non experienced high school wrestlers versus kids that have experience prior in grade school.
The other major reason is coaches pushing their kids to only play one sport. They want them to "work out" and focus on one sport. This is a complete joke and now you are seeing all of the literature and professional coaches coming out and speaking against specialization. I hope to see this change, but ultimately you need different coaches with friendlier philosophies in pushing for multisport athletes.
Again, I can't speak for other schools, but I can speak from mine. This is what I have seen. I am working on changing both for sure, but it is a long term solution of building youth up and waiting for them to get to high school.