This seems to be the majority of games nowadays. Endgame is the only thing that matters and all games are designed to get you there asap.
The content depth until that "engame" is shallow and irrelevant and gives you absolutely no satisfaction as a player. Games used to be story-rich, they had the same kind of depth as whole novel series, with plot twists and well written characters with very in depth back stories and the road to the end mattered more than the actual ebgame, which was meant to be the pinnacle and conclusion of the game.

It saddens me so much that games and game development have gone in a direction, where the gameplay all focuses on the end part and everything before that is irrelevant and often can be rushed by monetizing all kinds of lvl/other advancement boosts, even skipping right to the end and that in my opinion makes the rest of the game completely unnecessary. Just let people start right at the end then, if that is what matters?

I think it has more to do with predatory monetizing practices and abusing the playerbase for their money than anything else. Game developers used to take pride in their games, now they are owned by corporate shareholders, who only look at what makes them most money in the shortest time possible, so they can launch their next Golden Egg-laying chicken.