OP, 10's
USED to be the most ridiculously OP Stat scaling Level in the game (back in TBC/WotLK). You had 10's with 100% Dodge, Haste WAAAAAY over 100%, 100% Crit is easy even still, and all the while huge Health Pools due to various temp buffs that we all spent Hundreds of hours farming. 10's were the first very low levels to down the Fel Reaver in HP (yes I know other tinks have done it, but nobody lower than 10 as early as we did with 10's).
10's also
USED to be stupidly OP in WSG (the only one we could do way back then). In fact, I'm fairly certain I remember that the XP Off BG's were created due to all the complaints Blizz got against LvL 10's insta-jibbing fluffy casuals all day long. In WoD 10's are no longer "OP" in BG's but who knows, they may be again in Legion so don't neglect your BoA Shipyard Rings, Returning Defender Trink, etc.
As for the hate against 10's, that's 100% due to the
'19's Master Race' group of circle jerks. Hell there were LvL 1 tinks with PvP Achievements that NONE of the 19's had back in the day, but ofc they're the center of the Universe and nothing else matters