That is a rather ungenerous way of interpreting the article. Personally, I read it more favorably, as the party wizard won't be able to force down the door with a Strength check (but that doesn't mean he won't have other options for getting around it).They really seem to think that unless you have a really strong character in the party who is able to force a door open, a wooden door will be a challenge for a level 20 party. Which means they apparently do not think all the other ways to deal with a door, mainly, hacking it to pieces, are applicable.