I find this kind of thing particularly questionable because I like many people am often dealing with documents and text which I do not have the right to share with anybody even if I wanted to.
I noticed via the link from another comment that "work" and "schools" can turn it off - though not exactly easily.
Are we heading for a situation like smart TVs, where individuals are wrapped in the net of data collection but companies can pay extra to not be spied on - so they don't kick up enough of a fuss or stop using the vendor.