Steven: What you write is all true in the vast majority of stores.
But, . . . .
I was an early convert to REI after going shopping in 1976, when I was a boy scout, and someone in the boot department told me to buy a lighter and less expensive boot than I had planned to. One reduced sales ticket can equal decades of loyal patronage.
When I was working in a backpacking/ski shop, my goal was not to necessarily make the sale (that day), but to make the customer glad they came to our store first. If they needed a different item than what we sold, I'd tell them so, and tell them where to get it. Fewer sales that day, perhaps, but there were a lot of customers who would start at our store, even for stuff we didn't come close to carrying (like specialized rock or ice climbing gear).
For me, when I'm a customer, I don't want to wade through aisle of crap, a la Walmart to find the few quality items. I'd rather go someplace where everything has been pre-screened for quality.
That was also my modus operandi while working in computer stores in the 1970's. But that another era and computers are now a commodity, not a purchase researched for many months. And, yes, nerds do need to learn how to do the ask and wrap up a sale.
One of many problems is that commissions work, in the short term. Sales are up. But the experience is less pleasant and often less productive for the customer.