It doesn't matter if it's a celebrity but speaking for myself, the way I found to FFXI was pure luck. There were no advertisment for FFXI in germany, nothing not even in game magazines were articels about it. The online reason I got to it was the package at a shop. I saw it and bought it without even watching what is was, it's FF and for PC, holy jesus, that was enough for me. Not suprisingly I was shocked after I've installed it and noticed that it's an online game.
Some more advertisemnt then in the past will get people to take a look. If they stay is an other story.
The medium and player base has changed. Putting an ad in your typical video game magazine attracts just those types of people i said before. Putting out information about your game in that game magazine attacts people who will like you game for the mechanics of it.
Like i said, what has brought me and my friends back to wow at times has not been the ad in the nuklearpower banner. It was the interview i read on a website where bliz has said "hey, we are changing this because of".
So yeah, people can keep blaming ads and ad campaigns for whatever reason they want. The fact remains that it is a copout reason.
If you are a final fantasy fan, you will know about ffxi or ffxiv. You wanna know why? Because ffxii and ffxv exist / will exist, which tells you that there is something you may have missed somewhere.
If you are an mmo player, you will know about ffxi and ffxiv because you tend to read information about these types of games (be it on forums or gaming websites). Or you talk to your fellow mmo players who may mention these things (as well as other mmo's).
So yeah, those people who respond to ads might take a look. But what is there to look at if you do not release information? What is there to look at if your devs do not talk to your playerbase?
The ad, and player reactions and reviews are the only thing to look at. Now, do you want someone to join the game and party with you who was impressed by a flashy ad or heard that "this game will be the wow killzors!".