Snow Leopard had problems when it was released. I recall major issues with Mail and WiFi, among others. It was especially frustrating because Apple had made such a big deal about how 10.6 was going to focus on stability and fixing bugs.

Of course it did become very reliable. We remember Snow Leopard that way now, because we remember the last stable version of it. El Cap is very stable for me today. High Sierra certainly still has a chance to get there too.

So, I agree with the GP that Apple has never been in a place where they could release v0 of a new OS X major version without issues. That has certainly not been my experience. I always wait at least a few months before upgrading, sometimes longer.