HS100 can only be plugged in socket......Couldn't you use HS200 on this switch?

I want the HS200 to control the HS100 smart plugs so that I can turn on/off the devices plugged into those plugs by pressing the switch. Then I will have three ways of controlling the plugs: through the App, by voice through my Echo or manually by pressing the switch. I was able to do this with the Skylinkhome switch and plug system I had before, so it's annoying that the TP Link switch can't directly control devices. The literature about the switch is confusing: I read this FAQ and took it to mean that the switch could manually control devices linked to it:

[FONT=AktivGrotesk-Bold]Q: Can I manually turn on/off the lamp/other devices via the switch on the HS200?[/FONT]
A: Yes, when the HS200 is connected to the electrical system properly, you will be able to control the lamp/other devices in the system manually.

But it looks like it cannot control devices in the system manually unless I am missing something.

Manually in this context is usually taken to mean by the device's switch - what you describe would be automatic operation. Skylink is a hub system, TP Link is hubless so they're not comparable. You can either use a hub hosted on the internet (group them in alexa or use IFTTT) or an aftermarket app like mine (there are others too) to provide a local hub function.

While Skylink requires a hub for its full home automation package, its remote wall-mounted switches (no wires, run by battery) can pair directly with its smart plugs: I did not have a hub, just one switch mounted on the wall inside the front door.... when I turned it on, four lamps in different parts of my apartment turned in. The drawback was that it wasn't on a hub so I couldn't link it to my Echo... I could have got a hub for it, which would have allowed voice control as well as retaining manual control of my devices (and with the benefit of hindsight, I'm half-wishing that I had done that) but I went with the TP Link system because it looked to be more flexible. Except for being unable to pair my smart plugs directly to the switch. I have everything set up through my Echo hub so a simple voice command will activate the group. I wished to retain the manual function so that visitors, friends and other family could just push the switch and turn the lights on without having to be instructed in the correct phrases for Alexa!