Assemblers for DSPs go so far as having arithmetic operators like "+" and "=" in their vocabulary, as well as allowing things like hierarchical braces as syntac

Assemblers for DSPs go so far as having arithmetic operators like "+" and "=" in their vocabulary, as well as allowing things like hierarchical braces as syntactic sugar if you want them. But you are intended to write assembly for them, so making it almost C-like has a lot of benefits. The real answer is that nobody is supposed to write assembly, and the way the instructions are written is very easy to parse. The only core that doesn't have the "it's ancient and we didn't know better" excuse is RISC-V, IMO.