I think there's a solid case for someone to make a monitor with a working, built-in dock. I mean, many monitors already have USB-outs for keyboards and 2nd displays and such.

I think monitors are a sweet spot - they tend to stick around longer than computers, and docks really don't need to change a lot over time, at least now with thunderbolt out there. Fewer cables, too.

I like the idea of standalone docks, and I purchased a few, but none reliably worked for me.

I have a Samsung Odyssey Neo G9 monitor which basically does this. It basically has a simple KVM built into it. So my keyboard and mouse connect to the monitor, but then the monitor is connected to my desktop and a laptop. Using the monitor controls, I select which system I am using and get the display for that system as well as the keyboard/mouse activated for that system. There are different options for having them both on screen at once, but only one active for the controls, but I don't find that as useful as just having one system at a time being the sole focus.

Some monitors kind of do this. They have usb-c connectors for laptop video and charing and can do kvm-ish stuff, having a usb hub for talking to a keyboard and mouse (switchable between inputs).

look for dell monitors with kvm

Apple's monitors fill this gap, but they are obviously quite expensive

Could not agree more it makes a ton of sense

Dell has a few. I have the U2723QE. It reliably wakes up my Windows desktop but waking up my Macbook is a crapshoot. I'm pretty sure the issue is in Apple's software, not the docks.