أنشئ حسابًا أو سجّل الدخول للانضمام إلى مجتمعك المهني.
Because those are the people they craft all their activities for.
To know their needs then be able to satisfied them
you can not be in a relationship with someone you don't know nothing about him/her so data are important :)
Because it's a base to create engagement, offer, advertisement etc. shaped for particular type of customers.
Full Agree with answer given by : Sidrah Nadeem