This is one of those “does it really matter?” moments. Hi Quinn, Long time reader first time caller. :) Kind of surprised to read you asking if this "really matters". Yes this really matters. People in the thread have touched on why multiple instances being launched is annoying (makes debugging difficult, locks resources causing undesired behaviour, leaves behind terminal windows). But beyond that: XCode is a piece of software that feels very neglected. It crashes all the time. SwiftUI previews routinely fall over. It feels very neglected. So Apple pushes a bug. Hey, we're all software developers -- it happens. But to have someone with an Apple logo next to their name come in and say "yeah, the software doesn't work right, but it's not that bad", when XCode already feels like it doesn't get the care and attention it needs doesn't feel great.