vmandr
Think of atc as 'traffic police'. they are there to enforce regulations.
I spent 40 years in ATC in the UK, I was never a policeman. I was there to prevent collisions.
ARO is -usually- part of ATC which enforces ICAO and country rules and regs.
So ARO has executive authority.
They are not policeman either.
Often though to avoid arguing with 'pussy' pilots or dispatchers, they just call the GND/TWR controller, very difficult to be reached, and when clearance is requested, the involved are informed of the ATS rejection of that flight plan. If the individual still persist, police follows...
Tosh in the UK
Mere FPL submission, does not make it a 'guarantee' the flight will operate.
IFPS in Europe rejects dozen 'wrong' FPLs every day.
For routeing/traffic reasons. Nothing else.