It still happens. You need storage a TB or two with unlimited (or at least very high) traffic? That's not an issue. Even I could help being a mirror from home. But I wouldn't be surprised if there would be some free tiers already from cloud provider.
Half PB is a bit more than that, and I guess it is expected to grow... in 2023 it is not realistic to throw such storage around for free (+mirrors). It will be realistic in a few years considering that the storage prices have been in free fall for the past 30 years, but that time hasn't came yet.
(As a maybe interesting comparison, Debian's mirror is around half TB: https://people.debian.org/~koster/www/mirror/size )