I've "onboarded" (enterprisey word for orienting/registering/supporting/creating accounts for new hires) many new employees disoriented/frustrated by their new org's tools.
What often happens when a new hire really disagrees with his/her new tool for task is that they only use it for the "last mile" of the transaction.
So... say they have to turn in an expense report in Excel template. But they like some other app. They will take all their notes in $preferred_app, do all their editing in $preferred_app, and at the last step, export to Excel template.
You should see the machinations I've seen around mail. Convoluted downloading and parsing from Exchange servers with shell scripts... hah.
In any case... this is not ideal. What this does is make users absorb complexity for IT. IT can get comfortable wtih a platform, too leery to try something else. But users, often years into new generations of workflows (not just young people, so many older employees have been using Gmail for years in their personal life for example.), absorb the blow.