Realistically, you could experience all the game content in like 200 hours. Even faster if you know higher level players that can help you, which a lot of higher level players will help you. That is a lot of content without the limitations that purposefully slow progression down like you see in MMOs. Keep in mind that you don't need the game subscription to play the game and don't need to spend any money in the game to play and get the endgame content.

It isn't until you are trying to grind out getting certain things that your playtime skyrockets, but that is true with a real MMO.

On the subject of the community and players helping players, the community is pretty great. I have dragged lower level players through the hardest part of the game and taken them from level 20(you can start the game at level 1 or 20) to over level 100(there is no max level) in an afternoon with no detriment to my enjoyment. I have given newer players thousands of scrap, hundreds of legendary mods, and hundreds of thousands of caps worth of item plans that you can on get with RNG grinds.

I am not exceptional, I am pretty typical for the high level players. Since we have "nothing left" to do in the game and understand the meta, pretty much everything has lost value. We will buy overpriced stuff for sale in player vendors just because we want to get rid of caps and it takes us minutes to go from 1k caps to the 40k cap limit due to the value of the "crap" we have in our stash. Some players can't hit the cap limit in hundreds of hours of play. It could take you hours to get enough material to make 2k of ammo(that you can burn through in an hour) and we will give you 10k of that ammo or enough materials to make 10k and not even notice the loss because we know how to net gain ammo.

Compared to gacha games and actual MMOs, FO76 is far better in terms of cost in terms of time and money, also the community is very helpful to new players.