What do you think could have prevented its downfall?
Thus, the reading experience was fantastic.
As soon as they opened up to everyone, almost right away the quality dropped. All of a sudden Medium in particular was chock full of shallow "man page disguised as a blog post" posts and "tutorials" from people trying to build their own personal brands. It became a firehose of mediocrity.
Substack is currently experiencing the same cycle.
Ultimately I think, if you want to preserve the elite/luxury/exclusivity reputation, you need to impose artificial scarcity and resist the urge to "hyperscale" or whatever.