The people that required desktop like compute power either got a laptop workstation like Thinkpad W series (now P), or some server connected via RDP.
Apple just needs to have a docking station on their offerings.
But they do, it's called Thunderbolt, and they were the first manufacturer to really buy in hard.
For any laptop that can run within the 100 watt limit of USB-C charging there's little to nothing a proprietary docking solution offers compared to TB3, and even those that require more power can still use a TB dock just with one additional cable to plug in.
Yes there are a lot of crappy Thunderbolt and/or USB-C docks out there, but it's not like proprietary docks were ever bug-free either. At least now you have a choice of dozens of vendors rather than being stuck with whatever the laptop OEM wants to offer, and changing model lines doesn't mean buying a whole new set of docks.
It's still very common for companies to supply desktops to lower paid desk workers that don't work from home. The total cost is lower, fewer failures, etc.
The iPad tablet form factor will eventually hit limits in screen size. Is a 15”, 24” or even 27” tablet really feasible? If eventually the iPad becomes highly usable in docked mode with a keyboard, why not bring it out in a full clamshell or even desktop form factor?
Looking at it this way ok, maybe the Mac will move to ARM, or maybe it won’t. The thing is in the long run it might not matter.