Emerikol
Legend
Just to point out that this is how I have always interpreted the 4e skill challenge DC table. That the level of the skill challenge in question is based not on the PCs level, but on the level of what the are attempting to do. Trying to ambush Orcus in his lair is always going to have DCs associated with a high epic skill challenge, no matter whether the PCs are low paragon or high epic.
While a very easy fix and hardly worth crying over, it is illustrative when even you houseruled this approach.
I think if they had said it in a different way. Something like...
The DC's tend to rise as PC's level and take on additional challenges. This increase in DC though reflects the greater challenges they face. In no way should the exact same challenge at 7th level have a different DC at 13th level. Rather to use a trite example, the DM should use a wooden door at 1st level and a adamantium door at 13th level. Also bear in mind that increasing every single DC throughout a dungeon may affect verisimilitude. It is fine to occasionally have lower challenges that the PCs blow through without even having to roll. Instead of having an unlocked door like you would at 1st level, you can have a locked wooden door at 13th level. At that level they are both essentially unlocked.
Now. I am a static DC guy and prefer that philosophy but the above I think would have represented their philosophy better. RAW I believe does not bring this out and in fact says differently in my opinion.