This. There are categories of embedded system that don't allow reentrancy; it must be possible to represent the program's callgraph as a DAG with each function appearing exactly once. In some systems (ADA?) this allows for the preallocation of all local variables, too.

Some hardware (e.g. the smaller PICs) has poor support for pointers which can make indirection cost quite a lot of instructions.

Then there's the general principle of cutting your coat according to your cloth. You don't use a generalised pointer-to-rocket-engine system because you aren't going to add more engines at runtime