alt Hacker News>the fact that it scans for specific extensions sounds more like a product of an API limitation (i.e. no available getAllExtensions() or somesuch)
Why should a website be able to scan for extensions at all?
Or if there's a legitimate need (like linkedin.com wants to see if you installed the linkedin extension), leave it up to the extension to decide if it wants to reveal itself. The extension can register a list of URL patterns it will reveal itself to. So the linkedin extension might reveal itself only to *.linkedin.com, a language translation extension might reveal itself to everyone, and an adblocker extension might not choose to reveal itself to anyone.
that's basically how it already works...
extensions choose on which site they're active and if they provide any available assets (e.g. some extensions modify CSS of the website by injecting their CSS, so that asset is public and then any website where the extension is active can call fetch("chrome-extension://<extension_id>/whatever/file/needed.css" if it knows the extension ID (fixed for each extension) and the file path to such asset... if the fetch result is 404, it can assume the extension is not installed, if the result is 200 it can assume the extension is installed.
This is what LinkedIn is doing... they have their own database of extension IDs and a known working file path, and they are just calling these fetches... they have been doing it for years, I've noticed it a few years back when I was developing a chrome extension which also worked with LinkedIn, but back then it was less than 100 extensions scanned, so I just assumed they want to detect specific extensions which break their site or their terms of use... now it's apparently 6000+ extensions...