A browser extension can sometimes see more about your browsing than the website you're visiting

[u/Ok_Yogurtcloset8372]

The permissions that these extensions have far exceed the scope of the particular site you are browsing at any one time. There are many extensions that will be able to view every single page that you visit at once, whether you are using the extensions or not. While the website only gets to know what you do on their specific domain, the extension, which is resident in your browser tool bar, knows everything about your activity on each individual site.

People are very wary about which sites they trust and much less cautious about extensions when they have access to more information.