First of all, this is a topic that has come up for years and years about music "getting louder" in general. We're talking about compression here, not just "loudness", and you notice it most of all when you take a CD out of the player and the radio blasts at you, when you say to yourself, "shit... if only I could be THAT loud."
In defense of open, I've been doing my petty attempt at mixing for over 12 years, and noticed along those years how much "louder" music in general has gotten, simply due to the stereo compressor.
Today, there are many many [old school] engineers who argue about production not being as good today, because 1) today's engineers slam the levels so that there's no dynamics in the song, 2) the listeners' ears get fatigue from listening to an entire album and 3) today's engineers are just lazy, and they may resent the fact they had to do it all manually (my opinion).
I'll say it once, and I'll say it again... There is no "master" button. A practiced mix engineer will say that a better mixed song is one that was actually "mixed" BEFORE it goes to stereo compression. The old school engineers are simply stating that it DOESN'T NEED any stereo compression, especially if the instruments were compressed individually before the final mix anyway.
I agree with Open. If you listen to the album that's on his avatar, it's rough and crazy, and there are peaks and valleys that just jump out at you. Now that album--36 Chambers, Wu Tang-- (in case he's changed it by now) was produced by cats who used 4-track recorders and recorded a lot of that live, where you can hear the punch-in and outs, so that can either be a bad example, or the perfect example of what should or shouldn't sound good. The reason it sounds good is the same reason it sounds like shit: If you analyze it, you'll hear all the fkd up levels and how things are tossed together in this little melting pot of sound, old sample vs new vocal with little-to-no mixing technique. On the other hand, the effortlessness of the production allows you to throw out your analytical side of your mind, and you actually listen to the words in some sort of hypnotic, army-type-left-right sort of swing to what we used to call hip hop.
In the end, it doesn't matter if you overcompress or not. If your shit sounds tight, your shit sounds tight. You may uncover some methods that you may not be able to reproduce, and go platinum, while magazines interview you, while you bullshit your way through answering most directly of what your perfect recipe was, all the while not having a fucking clue to what you even did right.
But that's just my opinion.
P.S. I said this quieter than the last guy.