Why Microsoft as an example? They are pretty nuts about backward compatibility, including fixing other people bugs so their software would continue to run (the old SimCity bug). I believe I can still run Doom and, say, Ventura Publisher 3.0 on vanilla Windows 8 (although I'd prefer DOSBox, of course, at least for games).
It's true, MS cares more about back-compat than nearly anybody else. I was thinking there more of the "they'll use our platform whether they like it or not, because where else are they gonna go?" attitude that led to debacles like the Long IE6 Winter.
