Comment by numpad0

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 needed cabling.

This sounds like less of a problem for DCs with bare concrete flooring, but blades did fell out of fashion, so I guess the fractions of DCs with multiple levels or free-access floors were higher than anticipated.

(Also, maybe I'm just being an amateur, but I'd be scared of tolerance stacking with a "grape bunch" design like this. Individually enclosed chassis with cables and cage nuts are a lot more robust against dimensional issues)