As the article mentions, this isn't a security "feature," it's anti-competetive. The worst part is that Nextcloud isn't even really in competition with Google. Setting up a Nextcloud server isn't hard, but it's not a trivial task. Sharing it outside your local network also requires a bit of skill, especially if done securely. That is to say, Nextcloud users probably tend to be more tech-savvy.

The people using Nextcloud aren't going to suddenly decide to switch over to Google Drive. I'll get it from FDroid before I downgrade to Google Drive. If that wasn't an option, I'd set up an FTP server or even WebDAV.