Well for one you're punished for not using things on cd more.
Reaper is basically build gauge and spend gauge with few exceptions, it's kinda '' fail safe '' for a lack of a better term.
If you play MNK for example and don't pay attention to your Chakras or don't hit it fast enough it's a big deal but if you play Reaper and just zone out and don't spend your gauge it's generally not a concern unless you overcap.
Reaper is very forgiving in comparison to other Jobs, but I think some people believe that it's '' technical '' because you don't have a set point exactly where you need to do your spenders you have more choice.
But that doesn't actually make it more technical or difficult it does the opposite it makes it significantly easier and you need less awareness and attention to play it.
Edit: It's strange of the other guy to bring up DRG in a way that sounds so negative because DRG takes way more effort to play and I'd argue is more technical than Reaper.
There's more to weave and you need to know what can be double-weaved and what can't and when it's safe to use Jumps etc.
So it's a bit bizarre to present it as '' the devs made Reaper the technical pro job, not like that silly DRG ''.
Reaper is the Job you can zone out on and usually not be punished for it or just do 1 2 3 and forget about everything else while a mechanic happens and normally be fine.
You can't on DRG.