Earlier quoted context omitted.
It's not even the reliability which is the issue. Newer servers can put hundreds of cores in one physical machine, while taking up the same amount of rack space and using the same amount of electricity as older systems with tens of cores. How long do you want to run something that uses 3x the electricity for the same level of performance when you're buying power by the megawatt? How about the even older ones that use…
Yes that's a thing too, but it's a question of cost and potential revenue. So if replacement hardware is really expensive then maybe you make the inefficient stuff hang out longer, as long as it's not broken and you have paying customers. But at some point hardware does break and if you're going to keep the datacenter open for business you'll need to address turnover of inventory on an ongoing basis, and if you haven…
Exceptions naturally if you for some reason had an abnormally high failure rate, e.g. capacitor plague.