> I doubt anyone is going to MITM my access to an art historian's personal website.

But that is what ISPs did! Injecting (more) ads. Replaced ads with their own. Injecting Javascript for all sorts of things. Like loading a more compressed version of a JPEG and you had to click on a extra button to load the full thing. Removing the STARTTLS string from a SMTP connection. Early UMTS/G3 Vodafone was especially horrendous.

I also remember "art" projects where you could change the DNS of a public/school PC and it would change news stories on spiegel.de and the likes.