Don't beat yourself up over this. The Internet also sped the decline.
These businesses thrived on the oddball, low-volume, specialty stuff that benefits from central warehousing. Stuff that used to be the realm of specialty stores like Raspberry Pis are now on Amazon and a bunch of other online retailers, along with the various patchboards and DIY stuff. People post shopping lists for kits that you can then just assemble in an online shopping cart, and shipping cost is often lower than round-trip bus fare.
I think the store I miss the most of this genre was Efston Science on Dufferin