There was no specific reason given for why Friday the 13th was cancelled, although the article does mention that the poor performance of fellow horror movie Rings likely played a role in the decision.
Evidently the executives began to second-guess how Friday the 13th would do since it has the same audience and was also intended to restart a franchise.
Only a few hours ago, Paramount announced that it was removing Friday the 13th off its schedule, meaning that it would no longer comes out in October later this year.
Even if such a decision hadn’t been made, one of THR’s sources from the reboot said that production wouldn’t have been ready to go by March.