I only became aware of this sort of thing within the last few days, but an acquaintance of mine said that this sort of thing has been going on since circa 2014, which kinda shocked me.

In my humble opinion, if you don't know about it (know being the key definition, here), it's invasive, underhanded, 'black hat' and thus on the same level as malware/spyware, and it should be treated as such.