They do a surprising amount of business from local engineering firms, AV/network/cable installers, and little IT shops because where else are you going to get a 25 pair Amphenol connector, a quad op-amp, some colored heatshrink tubing, obscure batteries, and a 1% 27.1kohm resistor at 9am on a Saturday? They are expensive compared to online retailers (for small parts), but they carry Arduino and RPi and the cool-kids stuff too at only a small markup.
As a kid, the closest electronics shop to me was RadioShack (Radio Shack then) (and it was my favorite place to go). It was right next to where I got my hair cut and in the same shopping center as the grocery store, so I got to go at least every other week. Back then, they had two (maybe three) aisles of electronic components, copper clad PCBs for etching, ferric chloride by the gallon, both 40xx and 74xx series logic in DIP packages; all sorts of stuff. I haven't been in an RS for a long time, but last time I was there I couldn't even find a barrel connector and they used to have a dozen different sizes. Even in the early 90s I guess RS was an expensive store - a five pack of resisters was $0.50 or a dollar - but ordering on the Internet wasn't an option and mail-order was difficult if you didn't have a business account.
I miss what they used to be, but the state of the hobby has changed - most things center around a microcontroller now (RS never carried any in my recollection, though they did have some EPROMS ... maybe they had an 8051?) and I can do things with a half dozen discrete components and an Arduino in a few hours that would have required twenty or thirty TTL logic chips, wirewrap sockets, and a whole weekend not so very long ago.
I wish there existed something like a fusion between the traditional hobbyist electronics store and a modern hackerspace. Some place where I could go to rent time on a 3D printer, CNC machine or reflow oven and also buy the missing parts I need and get advice on whatever I'm working on.
I think the market still exists for walk-in hobby electronics stores, though I grant it's not an easy market to survive in. I don't have the answers, maybe the folks who own Baynesville do.