I think you're underestimating the degree to which day to day office crap weighs on people and makes them far less effective than they might otherwise be, even if they get to have someone come over and "pair" with them.
Remote working is an approach that really needs to be embraced by the entire company, and refined over time to match the needs and skills of the team as they change. Some people need more one on one time, some need more group time, maybe you do some face to face meetings quarterly instead of annually. It's not a one-size fits all, but nothing (including f2f office work) is.
One of my old start-ups had white boards everywhere (when we ran out, there were windows...) and ad-hoc bi-lateral marker-of-death struggles would spring up anywhere all day long. That was super handy.
I've mostly been an independent lone-ranger type for a long time now, and have rarely met most of my clients face-to-face -- but I do miss at-the-drop-of-a-hat white board sessions.
I like f2f problem solving too - whiteboarding, high energy, etc - it has its place.
And those companies aren't billion dollar companies either.
"All those teleconferencing/videoconferencing/virtualwhiteboards/etc are not as effective as everyone sharing the same physical workspace"
But they're more effective than those people not working together at all.
"Remote workers even with today's fanciest collaboration technology is not the answer to finding the best talent."
You have to define 'best'. If the definition of 'best' has to include "people who are willing to uproot their entire life to spend a portion of it in someone else's office", then yes, you're correct.
"I see no evidence that this has ever been successfully done. Small scale modest businesses, yes, but not big ones."
I see little evidence that co-located teams are all that much more successful at becoming billion dollar behemoths than virtual teams.
You get access to a wider breadth of experience of worker when you embrace remote. Just because management hasn't had enough experience with the model yet to be able to grow a billion dollar company doesn't mean a) it's bad or that b) it may not happen in the future.