[ReactiveJelly]

Yeah I've been wanting to have that "comment on anything" for a while.

It's possible in technical theory. But sharing the comments would be hard. Federation might work. Spam moderation could be hard. And most websites refuse to go into iframes, so your options are limited to browser extensions, SOCKS proxies, and Opera Mini style apps that re-render the page. Which means you'll get less than a percent of a percent of people to use it.

[flir]

Ditto. I imagined it like leaving a post-it note on a page. If you found a fix for a product you could leave a note on the company's FAQ page. Problem is spam, in all it forms. Can you imagine political pages?

[joshspankit]

This has been floated out a couple of times, but there’s one more factor you’ve missed: The companies really want comments/reviews done by a platform they control and they will fight against 3rd party methods.

[shiroiuma]

If it's done as a browser extension, the way Keepa is (it's used to monitor price history on amazon.com), there's absolutely nothing the companies can do about it.