It is, since C has horribly deficient string handling facilities in its stdlib. But a compiled language is not necessarily C.

And, well, simplicity can be relative: if you already know language X, using it will likely be simpler for you than some other better language that you would have to learn first. The beauty of CGI is that its simplicity makes it a language-agnostic API, letting you pick the simplest language for yourself.

We had CGI program written in C in production in 1999 or thereabouts. Worked fine. The problem was, that there was only one person who could understand it and update it. It was ditched at some point in favour of PHP I think.

I don't necessarily find that adding a compiler step defeats the simplicity, if simplicity is the goal. It might be easier to use a language with better string handling than C, though.