From it's inception and the games that triggered the phrase to be used, to today, it means what it has always meant.
As others have said, there are MMO's MOBA's and many PvP games that have had this "feature" designed into them where players could and would literally spend real cash to buy power-ups of one form or another, to make it so they could not lose. This meant that for a few bucks your opponent could literally invalidate all your skill, ability, time you put into the game, and the only way you would have a chance to beat them is if you spent real money as well.
That is why this term is hated and has such stigma attached to it. take that away, and the phrase is a benign joke. and quite literally, P2W has no real place in an PvE exclusive game like DDO.
To simply have it mean to be able to buy with cash some auxiliary items you can earn in game makes the phrase totally worthless.
So don't be fooled by a few people who like to try and toss it out for shock value, with no real understanding of the phrase, why it has the stigma it has, or what it means, using the term P2W, is like any other phrase, if you toss it out without fully grasping what you are talking about, then you you're the one that looks bad.