'... define "expert" and qualify "users" - social-media apps on smartphones or things actually used in an office or real work/dev environment?'
I'd say by "expert" they are familiar with the basic interfaces used on many operating systems. Do they know how to create a word document without hand holding? More than likely. Can they create a basic spreadsheet? Probably. Do they understand how to use office (MS or open or whatever version you pick) to its fullest? No. My experience is that many millennials seem to think "expert" knowledge of such software suites comes easy and they actually have it but get frustrated quickly when asked to do something complicated (like db links, mutli-sheet vlookup or *gasp* vb macros ).
I find it easier to train 40 y/o + how to arrange and manipulate their data than I do anyone under 30 years old. Well... maybe not easier, but more enjoyable. It gets old trying to train or teach someone without any real attention span.