Way back when, 1986-ish, San Diego & LA was the hub of places to purchase computing things from. I was a local business back in those days so purchased from a number of distributors/retail stores in SoCal, including that place in Oceanside that became geeks.com, The online part, which of course did not show up until after 1993, was very useful to me due to their carrying things that were hard to find elsewhere, their pricing and replacement policy was great, and I no longer lived in the area so could not "pop-in" for stuff.
I really am not sure which 1k gorilla geeks is alluding to, because there has been a lot of them over the years. For example, tigerdirect used to be a source I'd purchase from until they totally screwed a large order. Ecost.com was yet another but their web site became a bear to navigate. And Newegg actually started out in retail stores in SoCal as Egghead, though I use neweggbusiness.com now. Another place I use for hard to find items is CyberGuys.com, which has a distributor side. When I need consumables, I go to go4supply.com. I used to buy cpu's and memory chips (remember those?) from thechipmerchant.com, another SoCal store that is online.
And that really is why so many of you may never have heard of some of the other companies I mentioned, because they started out selling only to VARs, VADs, OEMs, etc, though geeks is an exception because of their store you could walk in to.