If they were to separate their first party app updates and OS updates (release wise, they can still market them together), more people would be able to pinpoint "ok it's not the entire update since I was on it just fine for a month, but actually just the notes app updated yesterday eating battery randomly". At least for cautious users.
While holding back app updates to stabilize the early upgrade experience might work, it's also somewhat contradictory to the idea that they upgraded the apps and their features and upgraded the OS as necessary to support the apps and features.
Every update since then has felt slow, or introduced bugs. Perhaps it was because Snow Leopard came on a physical disk, so they couldn't "just ship it".
My personal record stood at a bit over one week spent observing a dark screen with unmoving progress bar in the hopes that this time it will actually finish the upgrade.
Microsoft does distribute beta versions of Windows for third-parties to test against.
Does apple do the same? If Apple doesn't, then it's Apple's we have to blame it onto.
Much like Windows devs, Apple devs need to pay attention to this. If your livelihood is dependent on a platform, not paying attention is on you.