"allowed" by the web browser, but almost certainly not by the end user. The law is pretty clear on this in the US:
> 'the term “exceeds authorized access” means to access a computer with authorization and to use such access to obtain or alter information in the computer that the accesser is not entitled so to obtain or alter;'
The problem, of course, is that by clicking on a LinkedIn link, you agree to a non-negotiated contract that can change at any time, and that you have never seen. If that weren't allowed, then this sort of crap would correctly be considered "unauthorized access":
https://browsergate.eu/how-it-works/: “Every time you open LinkedIn in a Chrome-based browser, LinkedIn’s JavaScript executes a silent scan of your installed browser extensions”
Well, they're able to do it; “allowed” to do it is an ambiguous enough phrasing that it's practically begging to have an argument whose crux is fundamentally about a differing interpretation.