While we talk about gemming/reforging, the delta of stats is wy smaller - the effect of this "stacking" is small to the point it's negligible (to a degree). RoRO on the contrary give a freaking huge boost to one while bringing to 0 the other two. This means that the EP of the stat granted will go down a lot, and the EP of the other two will raise a lot (possibly becoming istantly better).
Sub actually is the spec which has the "worst situation" - all three stats are very near in terms of EP (which basically makes "viable" to focus on each one of the three) but their effects make also better each other. RoRO wuold break the balance hence making the stat boosted worse than it was.
Beware: RoRO IS a dps increase. Just is way smaller than it looks by the trinket description - rogue mechanics don't favor at all it.