I've had to deal with Comcast. I've known independent cable installation contractors, too, one of them being an uncle of mine - this being back when his crack habit was in full swing.

I find it a lot easier to buy a wide variance in skill and diligence among contractors, combined with a lack of QA oversight from their monopolistically disinterested corporate client, than I do some kind of shadowy, wide-ranging conspiracy to cloak deliberately anticompetitive behavior behind an obfuscating smokescreen of apparent incompetence.

Excessive splitters usually is a sign of ancient cabling as well. I know for a fact that Comcast has passive gain amps specifically built for dealing with homes that have more than like 8 tv's and a modem. You (or your dad, it's unclear) probably were hooked up a long time ago, or the tech didn't know what he was doing.