Well, your career has been built on your experience and specific skills which are valuable to any business, in particular, the one which has invited you to join their exclusive network!
Without a profile that details your skills and experiences, it's difficult for any organisation to understand your capabilities and how suitable you are for new opportunities. These opportunities could be for a few hours, to collaborate on a project for a few days, a short term contract or even a brand new job...
Even if you leave this organisation, you should still ensure that your profile is up to date so that you can work with them again in the future. That means that even if you're retired, on maternity leave or have finished a contract, they can still get in touch with you and make the most of your unique skills.
Remember, this profile isn't just about who you are today, but who you want to be in the future.