Now depends on what you mean by "skybusting " a lost art.
Are you talking about how hunters used to pour wax into shells or string large shot together to shoot at high flying flocks? I would say that that type of skybusting is and thankfully a lost art.
But if you're talking about nimrods shooting beyond their ability , no, that's alive and doing quite well sadly to say. Like in dove hunting the majority in waterfowling just can't shoot ,that with along with the fact they don't know how to place blind,decoys or when and how to call.
Some hunters "skyybusting " is shooting at anything other than a sitter where they are incapable of hitting anything on the wing.
IMHO anything over 45 yards is skybusting unless you happen to be one of the few capable of killing birds beyond that mark.