I will go a step further and say the people who think git should "scale" are wrong. The reason being that there are real tradeoffs that would need to be made. The vast majority of software projects should not be forced to use an inferior SCM just so that the few really large projects can be supported.

It's unfortunate that those people are forced to use Perforce... there's definitely a need for a "scalable" SCM, but git should not be it.