"He did this at a time when the market was going up"... therefore it's impossible and I don't need to try doing this and it's OK to just keep doing what I'm doing.
"He could only do this by living in poverty"... which would totally suck, so I'm better off not doing this and just continuing the way I am.
"He can only pull this off because he's renting his house, which is totally still work and therefore he's not really retired"... so this is all made up and therefore not something I need to think about or potentially emulate.
How about instead, we look at some of the things he talks about: Live as cheap as you're comfortable with, save as much as you can, build a stack early on and get to a point where you don't need to have a full-time job just to pay the bills.
That's all very doable, and it will pay off very much like the author describes. I followed the same path (a few years ahead of the author), and ended up in a similar place in my 30s.
Rather than dismissing this as impossible, the critics here might all be better served by taking a bit of it on board.