[peterfirefly]

The system might choose to use relocations for LEA and not for ADD -- this is of course not relevant for stack relative addressing and struct member addressing on the heap. I think I ran into this when coding assembler for DOS in the late 80's.

LEA also gets the "register + offset" thing done in a single instruction instead of two (MOV + ADD). It's also really easy for both assembler programmers and (dumb) compilers.

The "run in parallel" stuff is you looking at modern(ish) CPUs and thinking the original 8086 looked anything like that inside.