I'm pro Dev.to, but also pro Medium. What's nice about them both is that they are differentiated incentive structures so it does create actual choice for readers and authors.
But, I'm not sure what implosion on Medium you're talking about. That sounds like the talking points that two publications were using as they left medium (HN and FCC). But there was a shady backstory there and a lot of posturing to set themselves up to be independent.
But those publications leaving just ended up leaving a temporary gap that other publications quickly filled. Towards Data Science is now doing well north of 10 million page views a month. That's twice the size of Dev.to.
And I helped launch a new publication in May, Better Programming, that just crossed 4 million views per month.
I think when people here say that Medium decisions are user unfriendly that they are only seeing half of the picture. The paywall in particular is very author friendly. Now Medium brings authors both money and readers and you barely have to work for it. That's a good deal and creates incentives for a lot more and better writing. That end result is user friendly.