You are seeing a huge demand for more free speech platforms. Youtube is outofcontrol, Google is editing search, twitter is peering over the abyss now that Jack is gone and Reddit is right along them. It may take a while, but in a few years they are going to face steep competition. It may very well be an open source decentralized project like Mastodon.
As far as free speech platforms go you have things like Gab, Voat, etc which prioritize free speech in name. While that may be commendable as a value, the core audience they attract in the beginning is inevitably too extreme for the platform to go mainstream.
By the time Reddit replaced Digg, Digg was already losing users routinely. I don’t think any of the current social media players are in that position just yet.
While I think you're absolutely right, I think Digg made a number of other missteps with the Digg v4 launch that Reddit did not make. In particular, they shut down the old Digg site to reuse the servers for the new one, a mistake that Reddit was particularly careful not to make.
Digg was also already on the way down before their failed launch, and before the exodus to Reddit - a condition that doesn't apply to Reddit today. People have been making Digg comparisons about Reddit before I worked there, and now long after I've left. I don't think the 2 are comparable.
Will Larson writes about it here: https://lethain.com/digg-v4/