The Switch is designed to be used in more than one mode; it's a replacement for both portable and stationary hardware.
It's just an HDMI and charging dock. You could literally make one yourself if you really wanted to just by gluing a couple cables in the right spot to a piece of wood. Of course, no one does this because it's not really any more convenient than a simple HDMI cable.
The closest thing so far is 2-in-1 laptops
No, the closest thing is any portable device that has an HDMI port or other TV-out port. That's pretty much any tablet in existence, as well as devices like the OpenPandora and GCW Zero. The OpenPandora even predates tablets.
Then Sony patents this
You're focusing on the wrong detail. That it's Sony is irrelevant. Patents are a mess in general, and the only ones who win in the patent system are patent trolls. Nintendo probably has patents that are just as ridiculous, if not more so, but I would highly recommend against researching this, because knowing about a patent makes you much more liable if you infringe it. (Personal suggestion, not legal advice. IANAL.)
Basically, it's standard practice to patent everything possible if you're a big company. A lot of the time, these patents are just used defensively, to e.g. force a cross-licensing deal if someone threatens a patent lawsuit.