I agree with everything you said, but I still think "thousands" is way too low for newsworthiness. Social networks need a critical mass before they are good for anything. Surely that number has to be in the millions, right?
Well, Twitter was seen as a failure in 2009 compared to Facebook at the time. What constitutes to mass adoption is if several so-called 'influencers' try it out and if they make more money on the platform than both Twitter/Facebook and if the social network allows advertisers on there too. Then the millions of users will follow suit. Its that simple and it is has worked for Snap and it is working for TikTok.
If there is no gain or incentive for the famous users or the so called 'influencers', then the 'millions of users' will stay where the famous users are.
The "critical" mass however doesn't refer to absolute numbers. A million users with no relation to each other don't make it work. A few thousand with a tight network relationship cn make a busy place.
The metric relevant for social network sustainable growth seem unlikely to be total user count. It’s probably a mixture of metrics around inter-connectivity and rate of adjacent edge growth.
