Paywalled subs existed for ages already. If you had Premium or whatever it was called you could access them. It was mostly uninteresting stuff going on there.
I remember getting premium once (got a few days for free for some reason) and I think the only “premium” sub was r/lounge or whatever and it was just people saying they got premium.
To quote Cory Doctorow on enshittification:
Here is how platforms die:
first, they are good to their users;
then they abuse their users to make things better for their business customers;
finally, they abuse those business customers to claw back all the value for themselves.
Then, they die.
There is no content on Reddit valuable enough that I would pay for access to it.
If they were smart they would find a way to paywall all the years-old posts where someone is like “hey how do I fix this specific part on my 1992 sewing machine” and it has a single reply with the answer.
