I love excel, it's fantastic. I also hate excel, it causes me so many problems. Usually in the way of proliferating "shadow systems" of this sort:
Them: "We need you to do X with our data."
Me: "Okay, where do you see the data in the (enterprise ERP) system, I'll find the tables from there."
Them: "We use Excel because the system doesn't have a place for this data."
Me: "We upgraded 10 years ago. There's a place for it. How is office X getting the data they need from you?"
Them: "Oh we just share an excel file each week and they add their own stuff to it. Here's 300 weekly files for the last 5 years. We really need the analysis in a few days."
Me: ::tries to concat 300 excel files, discovers 50 variations on column arrangements, names, data types etc., tells department--:: "You aren't getting this in a few days. The good news is that you don't have to use Excel anymore because when I'm done, your data will be formatted & loaded into the ERP and all you'll have to do is put new stuff there too, and all analysis & reporting will be automated."
Them: "But it's the full-time job of one of our staff to handled all of this stuff in Excel."
Me: "Have you ever though that you needed more help in your department? Well, congratulations, you just got one 'new' full time employee."
People at least then generally walk away happy, except for me as I stitch together 50 variations on 300 different excel files. That's a slight exaggeration though: Most of these offline shadow processes aren't quite that large, and staff turnover is usually fast enough that such a process doesn't age 10 years past its point of obsolescence.