>There's "need" and there's "need". The person without the solid computer science background may very well be able to solve all the problems at hand, but the person with the solid CS background is far more likely to come up with the fast elegant solution that doesn't fall over in obscure corner cases.

I know the plural of anecdote is not data, but I'd say that the typical PhD that I have interviewed has generally poorer useful coding skills than the person from a similar background who stopped at a masters or even BS and then wrote a lot of high quality code during the time the PhD was doing a whole bunch of theoretical work.

>To use a concrete example for early in my career; I spent days and days trying to solve a problem by building a bigger and bigger pile regexps and if-else statements. Then my project manager (who had a PhD in CS) came along a just wrote a custom parser that solved the whole thing.

It's MUCH easier to come along after someone has already spent days exploring the problem and can demonstrate the dead ends, then say "oh, you need a custom parser" than to start at the beginning and do the same thing. USUALLY writing a custom parser is overkill and it takes a decent amount of digging into a system to know when it's not. If you start out writing one every time something looks like it can be solved by an "if" statement, you'd never get anything useful built.