Standing up and moving your arms has much lower space requirements than standing up and moving your arms while blindfolded and under a barrage of industry-leading illusions engineered for maximum distraction.
There's boundaries that the VR will put a red wall on screen if you approach. Setting them up is part of the installation of VR. I helped a friend setup Rift Oculus a while ago in a very small living room. Like bedroom sized living room. I've also played VR while sitting on a couch. Room is not an issue unless you play in a closet.
In a typical users playspace you're always near enough to the boundaries that they're visible. And speaking from experience, you do not want your VR setup within several feet of anything nice, like your television or hanging wall art, even if they're outside the boundary. As a good game of Gorn is guaranteed to make you run past that boundary and punch a nearby object.
Yes you can play some VR on a couch, but not Superhot, not Gorn, not Space Pirate Trainer. Very likely not Half Life Alyx.
I've used my VR setup from within cramped confines, but it's not something a non-enthusiast will do.
Edit: Also were forgetting a very important point mentioned above
"I'm not going to [...] lock my dogs outside just to play a video game."
