The only thing that matters is the checksum, because who cares if the destination address is not currently in the blockchain. It is obviously possible to send BTC to a new address which is not already there.
With that said the point stands that the likelihood of sending bitcoin to an unintended address due to a typo is very small. It's not as small as the article suggests, but it's still basically impossible (about 1 in 4.3 billion for a single character typo).
Perhaps the irony is that if you do happen to send bitcoin to an unintended address, you have a much greater chance of recovering it if that address belongs to a real person and is in use. If the address is not in use, then for all intents and purposes that bitcoin is lost forever.
The chance is about as high as the chance of generating the keys for a new wallet address and finding it has already been in use.
Or send to one that nobody has the key for
Additionally, you can prove you have the key completely offline if you want, which can suffice for collateral or pose authorizations
Most of these features of Bitcoin have been abstracted away for user friendliness, but are still accessible
if you know you know, solved problems (ratified protocols and standards) since 2012 or so
If I can physically see the inputs and outputs, it doesn’t take much to have a pretty good idea that it’s not bidirectonally compromising the cold wallet machine before sneakerneting them back and forth on a printed QR code.
I think armory wallet was the big thing for this? It’s been a while.
Meanwhile the best approach people commonly have today is a “hard wallet” that plugs into a usb port (yuck!)
I hope this doesnt become like email, where self hosting everything winds up blacklisting you in various ways