Let us try to dan lekaf zechus and say that those who daven at a late hour are busy with hachana for two hours. Do any of the chasidic sources say that hachana needs to start at a late hour? Would they not agree that if you know you are going to need that much time for hachana then just start your day early?
It also does not answer how this practice deals with missing the zman tefila. Even if you can say that bedieved the tefila works there is no question that they lose the schar for zman tefila.
How did zman tefila become the OK thing to fudge for Orthodox Jews,? The issue is not so much the fact that some people wake up late and try to justify it. The issue seems to be more in the INSTITUTIONALIZING of it. Many from jews speak badly about reform and conservative Judaism (and rightly so) for also institutionalizing the disregard of various halachos. How is this any different?