Remove threshold field from users table

Can anyone point me to anywhere in the current Drupal code base where the 'threshold' field in the 'users' table is actually used? I understand that this field was used once upon a time, a long time ago, to store the comment viewing threshold for each user (a-la slashdot). But I can't find any place in the current or almost-current code base (i.e. 4.6+) where this field is either checked or modified. It's loaded (along with all the other fields in the 'users' table), but that's it.

Do we still need this field? If not, I would suggest that we remove it from the core DB schema.