Are you saying that every project written in C has suffered from a memory leak issue at some point? Most C/C++ code I've personally written doesn't even use the heap.
I work on avionics and we use C/C++ now and then. We have a ton of rules regarding memory management (pretty much everything stays on the stack) and I can't recall anything I've ever been involved with suffering from a memory leak.
Don't need a leak for C code to be vulnerable, in fact not using the heap helps - just one missing bounds check on user input and you can write to the stack. OTOH, W^X should catch those.
I work on avionics and we use C/C++ now and then. We have a ton of rules regarding memory management (pretty much everything stays on the stack) and I can't recall anything I've ever been involved with suffering from a memory leak.