Why is LinkedIn required to use the platform?
One of the patterns that we have noticed in building a matchmaking platform and trying to weed out the good from the bad both on the client-side and the hero-side is that, by and large, people that don't have LinkedIn profiles are less likely to be a good fit for the platform.
99% of people interesting in hiring or being hired have a LinkedIn profile - it's a fairly common professional standard. There are the occasional outliers who do not have an account - and in some cases in specific geographical areas there are other professional networks that are more common than LinkedIn - Xing for example in Germany.
In those cases we can sometimes manually override the linkedin profile field with another social network, but we have also rolled LinkedIn authentication into the registration flow as of June 2019 as it's a much faster and easier experience for 99% of our users.