I've worked on projects in which both the front and end back end were written in the same language & those that are different. The former were more productive i

I've worked on projects in which both the front and end back end were written in the same language & those that are different. The former were more productive imho with developers working on both and with shared libraries & shared test platforms. The latter often end up getting silo'd with stuff passed over the fence. Yes many developers can do both, but its difficult to do both at the same time & even harder to hire for.