I think the very term originally used to stand for someone who basically goes for broke no matter the situation. Lately on MTF it has gotten a wider and broader meaning. Now it can also be used to describe someone who constantly hits hard with no real point construction.
Conclusion? There isn't a single player in the top 100 who can be accurately called a ballbasher, but people on here love to keep things simple. If someone plays defensively and tentatively, they push. If someone hits with loads of spin to have a high net clearance, they moonball. If someone hits aggressively, they ballbash. I've seen Del Potro being called a pusher as well as a ballbasher in reference to one single match on here.
It's a funny world we create and live in.