I think the 4e DMG pg 42 table should have explicitly stated baseline assumptions for "This is what a Low Heroic environment looks like", "This is what a High Paragon environment looks like" etc, to make the DCs & damage feel grounded in the world rather than free-floating. The GM could always move the slider if he wanted a Low Heroic game set in the Elemental Chaos. There is a little bit of this in the general Tier descriptions but it's not tied in to page 42.
Running high level 4e, I've also had a problem with "all monster abilities scale" vs the fixed DCs, rather than with arbitrarily ascending DCs. You get eg high level minion monsters that can climb walls like ninjas because their level & STR makes them great at Athletics, so they can swarm up regular DC 20 walls no problem. I can see why some GMs just have *everything's* DC scale by PC level, which is functionally equivalent to nothing scaling.
What I did with 4e was to create my own DC table based on the environment rather than on PC level, as so:
Easy Heroic: 10
Medium Heroic: 15
Hard Heroic/Easy Paragon: 20
Medium Paragon: 25
Hard Paragon/Easy Epic: 30
Medium Epic: 35
Hard Epic: 40
So eg navigating the slippery ice field might be a Hard Heroic/Easy Paragon sort of feat, that makes it Acrobatics DC 20.
With the usual +/- 2 for circumstances (so a particularly hard Epic task is DC 42 - unpicking the lock to Orcus' vault, say) that then covers every possibility in the official task DC table, which runs from 8 to 42, and I can keep it in my head and assign appropriate DCs on the fly without caring that eg my PCs are currently level 26.