Not being involved on the creative end, I'll just note that no login is required on AO3 unless the story is restricted to require it, something I have only encountered once. I know this to be true, because I don't have an AO3 account, but read there far more than FFn or TTH these days, and only slightly less than the SB/SV/QQ trifecta (all of which I do generally read while logged in, actually.)
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‎noli esse culus
‎noli esse culus