683 karma · joined January 31, 2020
I don't know though and am not aware of any docs going into detail here. That being said, sampling is really cheap. So implementing it in hardware wouldn't be worth it.
Much more importantly however, is that the cookie standards are a mess! The complexity of cookie default behaviour, their flags, scopes, differences in their SOP (cookies ignore ports for example, so https://example.com:443 and https://example.com:8443 share their cookies) are huge. Research papers have been written in this. And don't even get started on differentials between browsing engines.
This huge complexity of cookies opens up a whole class of authentication attacks where bad (or just weirdly) configured cookies can be stolen cross origin.
localStorage on the other hand is practically impossible to get wrong.