Earlier quoted context omitted.
I wish I could edit my post. Somehow everyone wrote to me about baldes. These are not the same, though. Blade servers were mounded into units of 4u, 8u, etc, they occupied a portion of the overall cabinet and still had to do "plumbing" for power and networking behind the chassis to the rest of the cabinet or to the rest of the datacenter. A full-cabinet blade rig would have multiple 8u blade units and some off the sh…
Forgot how I learned this but IIUC, blades failed because they expended per-rack weight and power budgets for datacenters with single enclosures. It turned out that you could compress 48U worth of computers into 8U or so, as long as you do not fill back the empty space with anything, because the cooling/cabling crawlspace collapses and circuit breakers will go off if you had done so. It wasn't because they still need…
I prefer to think of that was "datacenter weren't ready for denser workloads"; blades were ahead of their time, and their adoption wasn't great because of that. Since then, new datacenters have been built with more ambitious power/cooling/weight budgets.