The number of people that don't even own a general purpose computer is huge. And for those that do, ADB is a ridiculous thing to get setup for a particular device. I get paid to work on android software, and I don't even want to put up with the hassle.
Yes. And a bigger question is, why should I have to? This is a perfectly functional computer, it is more than capable of downloading a file and running it.
It's really sad that Apple and Google (and to some extent MS though they're just behind in this race to the anti-consumer bottom) happened upon this "solution to malware" (note: not a real solution) of "OS vendor vets and controls all software." It's a lazy way, it's an ineffective way, and it has made computers - incredibly flexible, programmable devices - more like cable boxes or telephones from past decades, that you had to rent from a monopolist and had no control over.
you don't need a computer to run adb. there's install with options
For now