Except there is a lot of content other than MSQ to do as you level.
The problem is thinking that end game is "the game" (thanks, Blizzard /s). That anything else in the game is worthless other than as a means to get to end game.
People play other games that have no end game all the time. None of the single player RPGs I used to play before I started playing MMOs had an end game. None of the RTS games I used to play had an end game unless you were gunning for ranks in PvP tournaments (I was not). None of the city building/simulation games I played had an end game.
You played the game, reached the end and that was it. There was nothing to do but start over again or play the repeatable content casually with friends.
What is end game in any MMO? It's a time filler to try to keep players subscribed (or buying loot boxes in the case of F2P MMOs) until the next content release. But there is also plenty of other content to keep players occupied.
This game has a massive advantage compared to WoW (can't say how it compares to the other popular MMOs currently out there). I don't have to wait for my friends to catch up to me to be able to play with them when they're just starting the game nor do I have to create a new character to do it. I can use my existing character and enable NG+. I can level sync for dungeons/trial/raids and FATEs so I'm not steamrolling through the content at their level.
If people want their friends to pick up the game, don't use the "we have to rush you to end game" method. Let them adventure at their own place and join them on that adventure.
If they truly have the "end game or bust" mentality (thanks, Blizzard /s), then pay for the story skip and job boost to get them close to it. Paying $50 to save 200+ hours of effort you don't want to do should be considered a bargain.
It's way easier to play with friends in dungeons here than in WoW.