If you do this through hidden forms then page navigation can no longer be done through hyperlinks and must now all be form submissions, which means a malfunctioning back button and logout when refreshing or opening a link in a new tab.
Please do not do this.
First party cookies are very useful and it's bad enough that people keep trying to replace them with javascript+localstorage despite the decades of security best practices that have been built into them.
I do agree that we can do away with third party cookies however.
The issue with this was that it broke direct linking to pages, or created such ugly and long URLs that they were weren't "sharing" friendly.
It was horrible, and cookies were (and remain) a much better solution.