Yes unfortunately they did do away with Power Leveling back when they implemented 7.3.5 and in Feb a Community Manager started the Massive Thread “XP FROM DUNGEONS” which has over 4600 posts now with people complaining about them taking away Power Leveling along with other XP reductions; On November 29th 2018 a Community Manager confirmed that Power Leveling had indeed been removed even though it had been a part of the game for 13+ years, You can view the CM’s post here:
Also if you look at the below link you will see that the XP reduction coming out in 8.1 tomorrow will not get us back what was lost in patch 7.0.3 and you can see that it’s actually an increase in XP in levels 10 - 39, See below link: