The telephone and electrical power networks were vast in scope (and still are), enabling interstate communication and power utilities. Echoes of the transportation utilities enabled through railroads. Multics was architected partially with the commercial goal of scaling up with users, a computing utility. But in a time with especially expensive memory, a large always resident kernel was a lot of overhead. The hardware needed a lot of memory and would be contending with some communication network whose latency could not be specified at the OS design time. Ergo, asynchronous I/O was key.
Put differently, Multics bet that computing hardware would continue to be expensive enough to be centralized, thereby requiring a CPU to contend with time-sharing across various communication channels. The CPU would be used for compute and scheduling.
Unix relaxed the hardware requirements significantly at the cost of programmer complexity. This coincided roughly with lower hardware costs, favoring compute (in broad strokes) over scheduling duties. The OS should get out of the way as much as possible.
After a bunch of failed grand hardware experiments in the 1980s, the ascendant Intel rose with a dominant but relatively straightforward CPU design. Designs like the Connection Machine were distilled into Out of Order Execution, a runtime system that could extract parallelism while contending with variable latency induced by the memory subsystem and variable instruction ordering. Limited asynchronous execution mostly hidden away from the programmer until more recently with HeartBleed.
Modern SoCs encompass many small cores, each running a process or maybe an RTOS, along with multiple CPU cores, many GPU cores, SIMD engines, signal processing engines, NPU cores, storage engines, etc. A special compute engine for all seasons, ready to be configured and scheduled by the CPU OS, but whose asynchronous nature (a scheduling construct!) no longer hidden from the programmer.
I think the article reflects how even on a single computer, the duty of the CPU (and therefore OS) has tilted in some cases towards scheduling over compute for the CPU. And of course, this is without considering yet cloud providers, the spiritual realization of a centralized computing utility.