>But it is also in the best interest of the end user. So why is that a bad thing?
Like said, the bad thing would be more wastage and potentially less relevant advertising.
The problem with advertising is that a campaign success is a multi variable equation that fiddles with human attention/retention of attention/memory and many other factors that makes us humans and regulate our perception.
For example, I don't consider Google Search contextual base. I put it in a category of it's own, because you're tapping into people declaring their intent and interest, and reducing it to context is dangerous - because it's more than that.
I used to say to clients: Facebook knows what you like, Google knows what you're looking for, and Amazon knows what you're buying.
Google does have Contextual Segmentation but it's used mainly for display advertising (GDN - Google Display Network). There was a time you could even select/exclude domains, but I don't know if that's still available.
Also, Facebook tried to leverage their data for display advertising outside of Facebook and they ended up closing Audience Network... so even interest based targeting seems to work within a context itself.
>The fact that publishers so far have not been able to do something about FB’s and Google’s duopoly doesn’t necessarily mean they will never be able to.
This would be a long conversation, but in a brief way, I think they tried to compete by placing themselves next to Facebook and Google, while they should have set themselves apart and leverage their strengths - name content quality wise.