All I can offer about this is my own experience. I am a player who is not really concerned with leveling up fast, I'm taking my time doing more questing, exploring, tradeskilling, etc. That being said I have become hooked and played this game with basically ALL of my free time since it came into early access.
I'm not a poopsocker but I'm far from casual either, and I am currently level 18. This was with two sessions of being power-leveled by friends as well as several pure grind sessions with groups on optimal mobs.
But since that isn't ALL I'm doing, I'm quite satisfied with the rate of progress. I've yet to reach my first hell level and so far I definitely feel like I've earned everything. The only thing that feels out-of-pace is the money and gear to level ratio, there does not appear to be a reliable way to get good quality gear besides player crafted items, and tradeskills go up so slowly that even while I am not caring about leveling up, I am very quickly outstripping my ability to craft gear that is useful or current to me.
Otherwise I must depend on drops from named mobs, which is the opposite of reliable. It's random, and you might not get it at all even if it does show up because you are likely grouped.
If people want to skip all other content to get to max level fast, I say let em. The type of player that wikis the most efficient solution to every single question never has and never will be concerned with the other activities like exploration or questing or finding game secrets, that doesn't mean there isn't content there to last you longer than 120 hours. It just means some people are going to skip 2000 hours of content and only do the leveling part.
This world is absolutely massive and I've barely scratched the surface. There is SO much to do, and see, and explore, beyond killing the same mobs for 5 hours straight until you can handle the stronger ones next on the list.