It's also pretty common for people to want their tools to be able to access a lot of external stuff.

From Anthropic's page about this:

> If you've set up Claude in Chrome, Cowork can use it for browser-based tasks: reading web pages, filling forms, extracting data from sites that don't have APIs, and navigating across tabs.

That's a very casual way of saying, "if you set up this feature, you'll give this tool access to all of your private files and an unlimited ability to exfiltrate the data, so have fun with that."