I don't disagree that if you can get away with just a local development environment that it is likely easier to get up and running. However, it requires good do

I don't disagree that if you can get away with just a local development environment that it is likely easier to get up and running. However, it requires good documentation of project dependencies and discipline by the team to not accidentally upgrade their version of PHP without telling anyone, both things that are easier said than done. Vagrant lets you codify that through "code". In the case of my employer, it's a necessity, but obviously everyone is different.