Seeing more relevant ads => good Getting your data sold to a data broker => bad free web sites & internet => good having to pay for quality content => bad (gee, who pays for NYT or WP after they're put behind a paywall?) Getting the best ads possible without any human involvement => good discovering the best products & services => good microtargeting => bad getting manipulated through political ads => bad Look, ads e…
They are the sponsors of the shitty part of internet. They usually lead to the creation of crap articles and websites that use SEO to grab and resell traffic.
I think that even without ad revenue enough people are willing to put quality content online that we don't need to fear. There are more reasons that making ad money to create content.