Before we have another concept, those from LispM, the "system" as a single entity of well_integrated stuff.
We have many example of those two way of thinking today: on "platform" side we have snap, flatpack, appimage, lx[cd]/docker, ... on system side we have Emacs, NixOS, GuixSD, ...
Well, for years the "platform" model seems to be the most reasonable, today seems ancient MIT&c hackers ware right, "system" approach is better. Simple to manage, for good software, do not hide bad practice, force collaboration etc.
On datacenters today and not from today we do substantially the same, in the past datacenters was a big collection of independent computers, now their are substantially all "a single computer" (even before The datacenter as a Computer by Google), made of many well_integrated components.
My poor English may not help, but I hope I have been clear up there, if so, what you think?