I have been an avid Guild wars player since guild wars 1. Over time the mount unlocking in this game has become worse and worse to the point where even just unlocking the new mastery for one of the oldest mounts in the game has become a grind with the XP requirement. The world trek-ing the figure out where the clues lead was enough but tacking the extra XP requirement after all of that is just too much. I could understand if all the mounts were always of use but so many replace others making them useless that making such a grind for a mount that would be useless after another one releases that does its job better makes no sense to me. There are MMO players from Super grindy MMO's like WoW and BDO even saying that they would rather do crazy grindy things in those games than deal with the way guild wars 2 handles mount grinding.
And I know what people will say to this already. They will make the same tired excuses for why Anet decided to handle mount unlocks such as Griffon, Rollerbeetle, SKyscale, and even the new MASTERY(which isn't even a new mount)for the skimmer. I guarantee the next expansion will have a new mount that makes all those other listed ones that you spent all your time grinding for obsolete.
and then there are those that have them saying that you don't need them whilst they fly away leaving you behind in map runs because the Original 4 mounts cant keep up with the newer ones thus the game tries to force you into participating in the long boring several day time gated rng based grind for the newer mounts.