The RV floor, wall and roof construction is a plywood/foam sheet/plywood (or fiberglass for roofs and walls) sandwich construction. The "sandwich" is what gives it strength. The thin outer plywood sheets or skins are like membranes in tension and compression, given strength by the foam core. In building construction, they would be called SIP, structural insulated panels. Anything which majorly impacts the integrity of the skins affects the strength of the sandwich. The floor system is probably screwed to a metal frame.
It's rather like plywood in theory. The strength of the glued up plies is more than the strength of the individual plies added together.
As noted, the best way, IMO, to fix your floor is to overlay a patch of plywood that extends several inches past the bad section on all sides, gluing liberally with something like Gorilla Glue. Done carefully, and filled and sanded carefully, it shouldn't be too noticeable, depending on the thickness of the patch.
I suppose there are other ways to fix this. Others may weigh in.
2014 Sunstar 31KE
1988 Suncruiser 31 RQ
1968 Travco 210