I have to agree. It's an perfect example of adapting to survive. Our Sainsbury was always a bit on the quiet side compared to other local supermarkets, but since Argos has moved it, it's been noticeably busier as people now have a reason to go there, and, as planned, buy other things at the same time as picking up their Argos order.
Same with WHS - people whinge about their High St stores, but they had the foresight to see the benefits of incorporating the Post Office counter when "proper" post offices in the town centre close, so that, again, drives people into their stores, who may well buy other things.
Another slightly different example is in-store cafes. We like the Morrisons cafe but hate the Tesco's feeble attempt and aren't keen on Asda either, so when we're on the road or holidaying in the UK, we actively seek out Morrisons to have our lunch or evening meal, and thus buy groceries, newspaper, drinks or whatever afterwards, so that's business gained by Morrison and lost by Tesco/Asda, simply due to "side-line" offerings.
I think it's got to be the way forward - stores need to have multiple sales channels to attract customers.