LinkedIn harvested peoples contacts under the guise that they were going to help you find connections, but instead they spammed your entire contact list through their outlook plugin and now when you try to get your lists and contacts out they make it extremely painful.
Again, I think you'd benefit from researching the Cambridge Analytica scandal to understand what's going on here. There was a time when social media worked according to the intuition you're describing, where you should be able to export from the platform any information you can see on the platform, and it led to results that the public and regulators really did not like. Companies like Cambridge Analytica were able to build detailed profiles on Person X, without Person X's consent or knowledge, simply because Person Y who happened to be friends with them agreed to share data with a Facebook quiz. So now that's not how things are done.
LinkedIn isn’t protecting people from misuse here; it’s preventing portability. If the concern were outreach consent, that could be handled with clearer user controls. Blocking access entirely keeps relationships dependent on the platform, which conveniently aligns with their business incentives.