What's the incentive for these manufacturers to do this?
Are they getting paid for the data (e.g. we'll pay you $100M to install spyware), or are they trying to be an ad platform, or is it simply analytics gone out of control?
They get to make money off of you for the rest of your life. They'll sell ads to companies, and they'll sell your data to anyone willing to pay enough for it.
Because they make higher margins on their ad business, details here: https://www.youtube.com/watch?v=6IFVTcM28KA