User blog comment:Kirkburn/Technical Update: July 1, 2015/@comment-126761-20150703153651/@comment-1251315-20150704135349

It's probably being cached in some way to reduce server load.

Last logged in date is not really all that useful to most people: the only thing it can help with is finding if you have sysops on your community who are logging in regularly to Wikia, but not editing communities which the community expects them to manage.