It started about ten years ago.
It isn’t such a major trend. How many people do you know who actually went there?
The cynical part of me wants to say what I know most people reading this are thinking.
The better part of me will say that all the marketing in the world isn’t going to make the grave of anyone reading this a place where masses of people will go to daven and people won’t be claiming that that they saw a yeshua after they davened by the kever of anyone reading this.
Rav Shaya MeKerstir was known as a tremendous machnis orech and baal tzedoka during his lifetime. A person overflowing with Ahavas Yisroel. And his brochas were known to have a higher than average chance of working. Therefore people feel his kever is a place to daven and doing mitzvas l’iluy nishmosey can bring yeshous.