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...
Yeah. I also think it was a bigger issue historically when programs were more likely to take a while to load, so you’d open something, do stuff while it’s loading, and then it’d be ready in the background.
But on a modern machine where you likely have an ssd, and potentially even an nvme SSD, a lot of times you just open a thing and instead of it showing up you get a notification 😅