From a lore perspective, it doesn't even make sense that flight masters exist in the Shadowlands, nor does it make sense that they charge gold for the service.

Grats, you've discovered that we're playing a video game with game mechanics and not actually living in a fantasty world that makes perfect logical sense.

By the way, if flight masters are a way to artificially inflate your time spent in game, then what isn't? Aren't quests a way to artificially inflate your time in game? What about having vendors in different cities? Or how about the time it takes to clear a raid boss? At that point, why can't our characters just sit perfectly still and have a big array of buttons to click in order to get the rewards we want instantly. Stand here (no travel time involved) and click this button (without having to use your precious time to do a quest) boom, quest reward. Stand here and click button, boom, you have the 220 trinket from Stone Legion Generals (no need to spend time fighting the boss).

The game is meant to be PLAYED. It's a game. And again, if you chock up playing the game to a conspiracy to steal your time, then you are openly admitting you don't enjoy playing the game and the game is wasting your time. And the only advice to give you at that point is to stop playing the game and find a hobby that you don't think is wasting your time.