The issue as I understand it, is that if you want to limit the amount of time that the user has to wait to a second or less (a reasonable assumption) then you c

The issue as I understand it, is that if you want to limit the amount of time that the user has to wait to a second or less (a reasonable assumption) then you can't use all that much memory with Argon2. So you don't get a lot of memory hardness.