Yes and no. People seem to forget that CPUs are not magical and can have bugs. On top of that, each processor family and processor stepping[0] have their own distinct bugs. (An example list can be found at [1], starting on page 8.) Well known incidents include the Pentium FDIV bug[0] and the more recent TSX bug[1] but there are a whole host of lesser ones that never reach the public consciousness because the OS works around them, e.g [2]. Needless to say, creating these workarounds takes time and effort and re-testing and that translates to money. And anything that costs money, well, ...
[0] https://en.wikipedia.org/wiki/Stepping_level
[1] http://www.intel.com/content/dam/www/public/us/en/documents/...
[2] https://en.wikipedia.org/wiki/Pentium_FDIV_bug
[3] http://www.pcworld.com/article/2464880/intel-finds-specializ...
[4] http://www.dailytech.com/Linus+Torvalds+on+Core+2+Duo+Errata...