So why don’t we have a current day geocities? Why don’t we have people building their own thing any more on a free hosting platform?

My guess is: part of that itch is scratched by social media, especially for people who don't have the time or knowledge to set something up. At the same time, you have platforms like Medium or WordPress which could be considered successors at least in some aspect. And they have tons of users.

Have a look into Neocities.