Apple is integrating more and more onto their (custom) motherboards. Memory and hard drives in some cases aren't replaceable at all. While it seems like a bad thing, it appears it's the new Mac way, so you'll have to just look past that.
The fact that they are in absolute control over their hardware, though, means they can do a LOT more with the operating system and ensure that everything works. The battery and performance improvements in the last few OS X updates have been quite amazing, and they targeted the specific hardware characteristics.
iOS is the same way with phones and tablets. Google doesn't just release an update that gets pushed to Android devices (at least the vast, vast majority of them) -- the update has to work its' from Google way through the OEM and carrier and in most cases doesn't even happen.
Apple can release an update that addresses certain issues or upgrades or whatever it may be and it will support all of their hardware (at least within the window of non-obsolete hardware) directly and it will just work, and it's entirely because they have absolute god-like control of their hardware.
The Windows world has hundreds of different makes and models, brands, etc., all with their own characteristics -- from a top of the line gaming rig, to a high-end desktop workstation, to a $189 eMachine. There is -zero- control of hardware, and a ton of room for software problems, including performance and compatibility issues, because of it.
To that end, I completely agree that Microsoft should step up and address the OEM bloatware that is so prevalent even still today, worse than ever, in 2015. While I understand that it's yet another lane for the OEMs to make money by shoving trialware down everyones throat, it's pathetic. And that's yet another thing that Apple is on top of -- you don't have your Best Buys, or Verizons, or anyone messing with your devices before you open it. It's pristine.
*sigh*... I'm not a fanboy for either. I promise. I'm just getting extremely fed up with how Microsoft is both handling these things and the direction Windows has been headed.