There is no PVE content or dungeon require spending to progress even in the earlier days. I never spend money to buy legendary gems or boost my reso yet I am still here farming at the highest difficulty available as everyone else.
How about you just try yourself now considering that you don’t need to pay to re-install the game? If you still feel the same after playing DI after re-install it, you can always uninstalled it. It is not like it will cost you a penny to do it.
If you ask me, it is always better for you to evaluate yourself than listening to anyone, especially from content creators nowadays where they love to make clickbait video where they exaggerate the issue so big to just to get clicks and views.
The major issue in the early days was that for acquiring some stuff there was only one specific method. Like set items, you could get specific ones from specific dungeons and that required grouping. If you were unlucky and didn’t get drops, you’d fall behind in terms of power and couldn’t advance to higher difficulty when other players did. As a result eventually there wouldn’t be enough other players on your difficulty to group with, stopping you from advancing further.
Things have changed a lot since then. A lot of stuff now have multiple means to acquire them. You can for example craft set items, craft 2/5 star gems, etc.
I originally stopped playing Immortal a few months after launch as I too felt like I had hit an impassable progress wall. But last year I decided to give another go and thanks to all catch up mechanics I was able to gain progress fast. I’m still not fully caught up, for example gear ranks need upgrading but I can do Inf4 content with relative ease. And I haven’t spent a penny.