I have continued to poke at Anti-Idle, and I have run into the same problem that others have cited about Guild Wars 2: there is a large dead zone between “have all your toys” and the cap. In Anti-Idle, that is actually thousands of levels, but it’s an idle game, so those can mostly happen while you’re AFK.
Once you reach the point where all the fights feel the same, you have completed the meaningful content. You beat the game. You’re done and can quit now. Also, when “RPG elements” has come to mean “character advancement,” it stops feeling like your character is advancing when you are just adding new numbers to old abilities. Again, game over, you won.
The sense I get from GW2 is that we are seeing the history of its development. (Entirely made up story follows.) Long before they abandoned the idea of horizontal progression, the original idea was like GW1: low cap, almost everything at the cap. Let’s give the characters all their skills by level 20. Hmm, people really like progression. Okay, we’ll match the industry leader and have 80 levels. Let’s push the elite skills back so we don’t have a 60-level dead zone. You saw a bit of that “needs more progression” when slot skills went from “all available immediately” to “buy 5 in this tier to unlock the next.” There must have been months of meetings trying to decide how to give players more toys over time without breaking the model of having one skill bar. There are some bonuses to unlock via talents, and your gear starts giving you more (not just bigger) stats, and … well, that plateau is kind of essential in the original notion of horizontal progression. Let’s hope they solve it before the coming level cap increase(s) and new tier(s) of gear.
GW1 had hundreds of elite skills you could capture, along with secondary classes, so you could pick your one bar of skills from literally thousands of skills. Part of horizontal progression is having the option to progress, more options not just ones with bigger numbers.