I'm not saying that removing nofollow for medium is the right solution. That would be inviting a horde of spammers on to the site. However, there can be better

I'm not saying that removing nofollow for medium is the right solution. That would be inviting a horde of spammers on to the site. However, there can be better solutions (such as the ones by StackOverflow). Content quality (which can be measured by medium) to allow good quality content have outbound links would be another. A simple start would be to have a whitelist of domains that can be considered authoritative (as suggested in the linked tweet). Yes, this is a hard problem, but it needs to be solved.