Let me level set this discussion with the following: If you'd have asked me this exact same question 2-4 years ago, I'd be giving the exact same answer as you are.
With what we know and the collusion between FedGov(Democrats & the swamp), Big Tech companies censoring, deplatforming and in some cases debanking those who disagree with them, the COVID-19 bullshit & lockdowns, daily propaganda that's spewed like a firehose at us daily vis a vis our Government, Media, Big Tech, and the ONLINE MONITORING of everyone thanks to Fascistbook's hooks into everything and their ability to track you without your even having an account on their "service", I can see why many think this is really about monitoring and control.
I cannot discount it 100% out of hand that this is purely an economic decision by the wireless carriers.
Could it be? Yes. Could it NOT be? Also yes. The creeping and blatant tyranny that's happening in this country should make us thoroughly question everything.
Given the time we live in and the fact that Government, media and big tech cannot be trusted at all at this point I think healthy skepticism and questioning is certainly appropriate.
Again, 2-4 years ago I'd have answered the exact same way you did. Today?
Nothing changed. That was the right answer 15 years ago when Sprint decided some customers weren’t worth the money. It was the right answer 1-4 years ago. It is the right answer now.
Really all you’ve done is point out the HUNDREDS of other, easier, cheaper, ways there are to track people in this world. Ways that have mostly existed for decades. You’ve really just given EVEN MORE reasons why such a conspiracy is silly. It’s laughably UNNECESSARY. They already have all the info they could want, from multiple sources. Disconnected 3G phones just don’t rate the trouble to do anything about.