On this page:

https://siterankdata.com/medium.com

You'll find a chart going back to 2013. It looks like 450 is where it started to level off after opening Medium.com. There is a clear leap around 2017 and it's been hold well since then.

In March of 2017, Medium introduced paid subscriptions. In August of last year, they introduced pay per clap, too. There seems to be a good correlation between the jump from 325 to 261 since they introduced author payouts, but I think that they were a strong site from the beginning.

I did change my tune in the last couple of days, thanks to comments here and posts elsewhere...

https://steemit.com/steemit/@digitalfirehose/steem-integration-transaction-demand-and-bitcoin-shorts

Thanks for your comment...