Locking stable flying but not skyriding to pathfinder is stupid

Because in this regard it negatively impacts game design as well.
Just the main Dragon Isle continent is the same size as all of Northrend.

You can do quests that go from one end of the isle to the other because of Dragonriding (now Skyriding). Without the speed of Dragonriding that’s not possible.

And you can’t put those tools to TBC flying for multiple reasons:

  1. If you make a convenience tool too powerful you eliminate all other things (see the Skygolem for Herbalists and the Water Striders compared to literally every other ground mount).
  2. Because of how it flies, one small tap going at 800+% … you have no control over that, at all. Which means that you need to reduce the speed even if you increase (like they have) TBC styled flying … but you still can’t end up in a situation where a regular continent is the size of an entire other expansion (because remember, DF also had Zaralakk Caverns and the Emerald Dream, both of which are zones larger than Dragonblight which I believe is the other largest zone to date otherwise - could be wrong about that one though).
  3. If you stand on the ground in the middle of Ohn’ahran Plains or in the middle of The Azure Span … look around you. All of those things are affected by the particular type of flying you have access to: the ground is curved, and in the Azure Span you have trees that are in the way.
    Previously, before DF, you couldn’t have curved terrain because you would hit stuff, or you would miss stuff, and you couldn’t have trees either because you would hit them as folks were afk when going from point A to point B not interacting with the game at all as they were afk.

No one cares whether you prefer or like one type of flying above another. What people like me care about is what’s actually good for the game though, unlike you. Because that is the basis of every single argument against TBC flying and why over and over again it has been limited or outright removed from people over the years.

Ever noticed how rares and activities sitting inside of caves were treated completely differently by the playerbase than those that were completely outdoors? I betcha you never thought of that. “Why go inside of a cave to kill a rare when I have to dismount for it”; rares inside of caves stay alive for much longer because people can’t find the entrances and don’t care enough to do so.

Because people spent their entire time in the sky not looking around on ground level.

Yes, how you play the game in this particular regard has a MASSIVE negative impact on the overall health of the game. That’s not disputable. Period.