I can't speak to why you'd want to use C in a web stack, but I can weigh in in the more general sense:

A while ago I thought I'd try my hand at the Cryptopals challenges, and I figured, hey all the security guys know C (and python, but ugh) so I'll use this as an opportunity to really learn C. Prior to starting that project, I "knew" C, in the sense that I took CS036 which was taught in that small subset of C++ that might as well be C.

So I jumped in and it felt really liberating, at first. You want to compare chars? It's just a number, use >= and <= ! Cast it back and forth to different types! Implement base64 by just using a character array of the encoding alphabet and just walk through it like an array and do magic casts! No stupid boilerplate like namespaces or static class main{}!

Then by about the 2nd set where you have to start attacking AES ECB I realized I was spending more time debugging my mallocs/frees and my fucking off-by-one errors than I was spending on actually learning crypto. I stuck with it until I think part way through the third set but by that point I couldn't take it any more.

So I bailed out of C and never looked back. I can see how a certain type of programmer (who is more practiced with malloc/fastidious with their array indices and loop bounds than I am) can really enjoy C for a certain type of work. But I can actually say now, hand on heart, that I know C; and I don't like it.