Comment by ethbr1

You're incentivized not to sell targeting data, but you're very incentivized to collect and maintain as much of it as you can, and then offer access using it as a service.

So, at the end of your day, company X has an overdetailed profile of you, rather than each advertiser. (And also, at least in the US, can repackage and sell that data into various products if it chooses)