Facebook has a good abstractions at all levels of the stack. This allow engineers to work on all parts of the stack without having to worry about low level impl

Facebook has a good abstractions at all levels of the stack. This allow engineers to work on all parts of the stack without having to worry about low level implementation details. I have not written a line of SQL while at Facebook. If there is some domain knowledge needed then I can just rope in an engineer from the appropriate team to review my diff. It's also worth noting that on product teams engineers tend to gravitate towards the parts of development they are more comfortable with, or enjoy the most. They are not forced to work with te full stack just for the sake of it.