if you look at the traditional RDM debuffs
Define "traditional RDM debuffs" please.
You mean: Slow, Paralyze, Blind, Frazzle, Distract, Gravity and Dia?
I wouldn't generalize. Slow II and Paralyze II are clearly stronger in the RDM counterparts, Gravity II as well possibly.
I mean there isn't a lot of testing about them, but eyeballing it seems to me there's a big difference in favor of the RDM counterparts.
Let's compare the rest though:
Evasion-
Distract III caps at -120
Indi-Torpor caps at -100 with Idris
But then you have Enf Magic Effect+ (caps at +60%, not sure if it gets reduced on NMs?) and Saboteur, which has a very short cooldown so we can assume it to be up 100% of the time. It won't realistically, but let's just assume it.
On NMs it's a ~37% potency increase. Supposing it stacks additively with gear, it's almost 100% potency leading to a bit less than -240 Evasion?
More than Bolster's Torpor (~200 reduction)
Meva-
Harder to test, but numbers should be similar to those of Eva-, with the small difference that it's currently technically impossible to reach the Enf skill cap while also mantaining all the Enf Potency gear in the related slots.
Again, another point in favor of RDM
Def-
Dia III with Light Shot caps at ~23% def reduction
Indi-Frailty caps at ~42% reduction.
Clearly RDM doesn't keep up here, also thanks to the fact that Dia's def down doesn't get powered up by Saboteur and Enf Magic Potency gear.
Accuracy-
Blind: caps at -50, couldn't find data on Blind II
Indi-Slip: caps at -125. Not sure about how much stronger Blind II is but I doubt it keeps up with Slip.
You never really see a GEO using Indi-Slip though, lol, but that's another story.
So tl;dr
Not all RDM debuffs are stronger than the GEO counterparts.
With that said, there's some very important differences to keep in mind.
RDM debuffs need to land (and that alone isn't always easy) and they can be dispelled. As a matter of fact, some NMs do it frequently, so frequently it almost becomes useless to even bother with debuffs.
GEO debuffs do not need to "land" and they can't be dispelled.
This aspect alone is an insanely huge pro in favor of GEO regardless of the potency (which isn't always so far behind RDM's, in some categories it's actually above).
It's so freaking powerful that SE had to ninja add Geomancy resistances of 50% and 75% to some NMs/Content, simply because GEO was too powerful.
So yeah RDM can sometimes have more powerful debuffs that can all stack together, but I wouldn't go as far as to say that it's an overall more efficient debuffer than the potential GEO has.