It is likely in response to scraping. Linked in is heavily scraped by scammers who do the BEC scams. So linked in is trying to find ways to link together banned accounts, to handle their ban evasion.

I run a site which attracts a lot of unsavoury people who need to be banned from our services, and tracking them to reban them when they come back is a big part of what makes our product better than others in the industry. I do not care at all about actually tracking good users, and I am not reselling this data, or anything malicious, it's entire purpose is literally to make the website more enjoyable for the good users.