Until recently, no reasonable person ever expected a major new OS release to be rock solid before its first major point-release. And actually nothing has change

Until recently, no reasonable person ever expected a major new OS release to be rock solid before its first major point-release. And actually nothing has changed, except that what we used to call a "point-zero" release is now called a Public Beta. Windows XP was sufficiently reliable by SP1, sufficiently secure by SP2, and sufficiently prepared for an extended lifespan by SP3.