Focus stealing prevention exists for two main reasons: One is security, since we need to prevent rogue apps from deceiving users into e.g. typing their password into another window. If apps can silently claim keyboard focus and open their own window over the currently focused one, this enables phishing and other similar attacks. The other...
This is one of my biggest complaints and all I hear when I read this article is excuses. They want the devs of the apps to implement a protocol that they just aren’t implementing. Or the app is old, or it’s running in wine, or… Or… Or… Or maybe this approach just isn’t working and they’ve made it everyone else’s fault.