I left dropbox when they changed the full page upsell to "dropbox business" so that I couldn't easily figure out how to skip it and get on with my work.
I had a paid pro account at the time.
I actually had a conversation with a product manager; I checked the yes you can contact me when I cancelled my account. They simply refused to admit that an upsell was a advertisement and that disrupting my workflow on my paid, professional account for an ad was wrong.
The other interesting thing about that conversation, they could not understand how a sole proprietor would see no benefit from collaboration tools and kept making up bizarre scenarios where I could use them.
I actually asked them if they were a product manager or a salesperson at one point.
To Dropbox's credit, that product manager didn't try to retain me, they were genuinely trying to figure out why I had quit; they just couldn't grok the reason.