[ellis-bell]

but then the heap would grow down in such a diagram...

btw my understanding is that the heap came first in the logical development of C and other systems programming. so it made sense to have .text and other program data at the lowest virtual memory addresses and then have the heap grow towards higher memory addresses.

then when the stack became a thing it had to grow down...

[monocasa]

The stack might have actually come before the heap in history, and actually proceeds any systems programming language that was a higher level than assembly. They were seen in the Z4, and Turing wrote about them in 40s.