Of the MMOs I've played, Warhammer Online, for all its issues, seems the closest to beating database deflation. Pretty much all levels, starting from level 1, are fun. One of the great features of WAR is you can que for tier 1 scenarios at level 1, fresh off the character creation screen.
One of my fondest MMO memories was doing that with a choppa. I got three insta-ques back-to-back, and by the the time I finished my first quest I was level 4, had an equipped piece of blue gear, had at least one set piece for the auction house, and was a member of one of the more active guilds on the server. From level 1 you do PvE, RvR, scenarios, and public quests, and it is like that for the entire game, and Tier 4 is no more fun than tier 1, and in fact tier 1 might have better balance and fewer abuses and exploits.
Beginning game or end game it was all pretty much the same game in WAR. I think the solution to database deflation would be to make a strong fun early game, where ¨leveling up¨ adds more content but not necessarily more fun. Keeping the emphasis on the early game is welcoming to new players and keeps most of the ¨data¨ interesting to most of the toons.
...On further thought, as you level up in MMOs, it is not like you gain new content, as much as you lose old content because it becomes irrelevant... which I guess is the point of this article.