This is not only about adding just another node or functionality – a full compositing tool needs lot more than that – just think about Nuke or Smoke etc, how amazing these tools are – If Black Magic declares Resolve as a compositing tool, it will be far behind in the race – so it is more honorable for Resolve to be a coloring tool and being at the front, rather than being one of the last ones and struggling in the race. I strongly suggest Black Magic not to make such a mistake and leave it as (one of the best) Coloring tool. They can always develop a separate compositing tool and then struggle and wait for years to come closer to Nuke and Smoke.