Really, so where are the home drives with a SAS interface and DIX/DIF? So I pay extra for enterprise drives because I want my drives dual ported.
Also when it comes to 2.5" drives I can tell you know the bog standard laptop drive is most definitely not rated for 24x7 operation. So yes you can build a low power home server with one, but don't expect the drive to last more than 18 month unless you fork out for the enterprise rated 2.5" drives which interestingly require a 12VDC supply rail to spin up and are 15mm deep rather than 9.5mm or possibly 12.7mm.
So I don't know when you used to design HDD's but you are talking rubbish.