Extensions like this exist for two reasons. The first is that people don't understand adblockers or that they can be used for this purpose. The second is their UI sucks for the layman.

I know how to do it in uBlock and Ghostery but that doesn't mean I want to or that it'll be 100% effective.

I was going to write an extension the other day to block custom responses in Slack, as they gets triggered way too often in one of the workspaces I am in. While figuring out the best way of identifying those messages I realized it would be enough to just add one line to uBlock Origin rules.

(for those interested: ##.c-message--custom_response)

Ghostery[1] also already blocks chat widgets.

[1]: https://www.ghostery.com/

though they have serious privacy issues and mine is completely open sourced.

Doesn’t Ghostery have serious privacy issues?

Yes. Ghostery gets some criticism - due to privacy issues among others.

https://en.wikipedia.org/wiki/Ghostery#Criticism

Of course; it’s proprietary software.

It's open source as of last year. https://github.com/ghostery/ghostery-extension

I just launched this as a filter list form, it's downloadable from the website https://hellogoodbye.app

I agree. This is a great idea for a browser feature, but for me personally, I would rather do a manual blacklist through /etc/hosts.

I have added it as a list form to download.

It's available on the website https://hellogoodbye.app

Unless you do it through a PiHole, or some homebaked Linux DNS, you are required to turn in your HN card.

Not possible. You cannot block a specific script by that approach.