Seems like an honest question. "Stupidly" is a key word there because humans are, without exception, vastly too stupid to deal with the combinatorial explosion that the heap presents. This is a key goal of languages like Rust: allow the compiler to deal with the complexity for you.

There are vastly fewer interacting elements when you restrict yourself to the stack: basically logic errors and pointer arithmetic become the key concerns (and Wuffs supposedly deals with the latter). Really smart people may be able to completely reason about this space.

Developers are known for imposter syndrome, but we have an unhealthy amount of overconfidence at the same time.