it's not really so much a brand name as just getting the concept out there. php developers don't realize that there are option when it comes to the runtime.

i would guess that the majority of them wouldn't even know to look for phpc or any alternative. there just hasn't been any news of something like HPHP before HPHP. if you want to run php, you go to php.net or install it from a package and go from there.

combine the above with very little actual need, very little public information on how to build a large site, and lack of maintainer interest and phpc just won't get major traction.

I would have loved to have found phpc several years ago when i was still working on a large site that had performance problems.