If a guy is riding away from you, how do you catch up as a rogue?
Even on my PvE server, when a flagged Ally was hovering above our shrine/Org/wherever, I was more than able to 'touch' them, multiple times in fact, as I flew above them, dismounted, cast corruption, switch meta, cast doom, demonic leap into meteor, repeat. How I laughed as I watched their unit frame as they flew away, slowly decaying to death.
Untouchable? No. A fun, killable challenge? Hell yes.
"But I'm a rogue!" Pffft.