The internet alone can't be blamed for these shops closing. It's the world econmic model that's changing. if a store/shop doesn't change, then it will get left behind. Ths doesn't matter if it's a dive shop or any other type of shop.
How many "TV/VCR Dealerships" are still in business? I remember when I was a kid going to the "TV Dealer" with my dad to buy a TV. You don't have those any more. When the first VCR's came out, you could only buy them at a TV dealer. Now if you want a TV or VCR, you buy it at a "Superstore" or online. It's the economic consumer purchasing model that changed.
As for dive shops, some have changed and some haven't. Even if they don't
have an "online store", they all mostly have a website. A dive shop without
a website for contact info, directions, etc., is leaving itself behind in the times.
Funny how they realize this, but still bash online sales (because it cuts into
their profits).
I would say that we've had more local dive shops here close due to poor
management than anything else.... most of them closed even before you
could buy stuff off the internet (10 years ago). We now have one left
in the town I live in and about 5 more in the 45 minute drive radius around us.
One of the stores 5 times more business than all the others since they
actually stock items and are price competitive with the internet. Mostly
because they operate an internet store themselves. So they've changed
with the economic times while yet another store announced it was having
a going out of business sale.