The best argument for "over the last 50-70 years" is that we've forgotten the poorer products of 70+ years ago. A recommendation: find a copy of _The Best of S.

The best argument for "over the last 50-70 years" is that we've forgotten the poorer products of 70+ years ago. A recommendation: find a copy of _The Best of S.J. Perelman_ and read the "Cloudland Revisited" pieces, middle-aged re-readings of the movies and popular literature of his youth. Not many of them linger in popular consciousness now.