Seriously, the defining aspect of most programming competitions is that you're making a program as fast as possible, whatever it takes. C++ rewards this: if you keep sinking an order of magnitude more effort into it, you can seemingly always shave off another tenth of a percent of the time. There are some cases in which this is actually relevant (many involving graphic rendering, a niche I work in, PS), but they're really a tiny part of programming.

It makes sense to code them in C++ (or C), but it's really not the best fit for more general development, which usually places a higher priority on being able to deliver an adaptable and correct solution.