I hate this too, but to continue the example, my actual real life bike shop struggled for years with bad websites sold to them by a succession of "developers".

The Facebook page appears to draw as much if not more business, and chap can run entire thing himself with no overheads. It's hardly a surprise some choose just to use Facebook really - as far as they are concerned its often "better" for them than the open web was, even if that is hard to swallow sometimes.

That's only a 'loss to the open web' if the open web somehow had an inherent claim to have that page in the first place.

yeah, "open" implies the freedom to choose to be hosted by a platform like Facebook if you want.

It would be a loss to the open web if, somehow, there were no alternatives but Facebook, but that isn't the case.

It took me a second on Google to find bike shops local to me that have web presences outside of Facebook. They probably have pages on Facebook as well (it would just be good business) but the web isn't a zero-sum game, one doesn't somehow cancel out the other.