I agree Scroll seemed very promising but I'm not sure how successful they were. Did they provide more income than ads from subscription fees? Meeting that goal while burning investors money is less impressive.

Scroll also used a browser extension by the way.

They had basically no investor money.

> Did they provide more income than ads from subscription fees?

Yes. That's literally all they did. You paid for a subscription, and they distributed subscription fees among the sites that you visited.

In return, you got an ad-free browsing experience.

By the time they got killed, it was used on Ars Technica, TheDailyBeast, TheVerge and some other major news sites.