The main thing keeping most businesses on their old spreadsheet isn't loyalty to Excel. It's fear of losing everything in it.
Ask any business why they haven't moved off their customer spreadsheet and the honest answer is rarely "we love spreadsheets." It's usually closer to: "we've got years of customers in there and we're terrified of losing it in the move."
A completely reasonable fear
Customer history is one of the most valuable things a small business owns, built up job by job over years. The idea of retyping hundreds of records by hand - or worse, quietly losing some in the process - is enough to keep most people on a system they've long since outgrown.
Why the fear shouldn't be the deciding factor
A proper migration path - importing existing records from a CSV export rather than starting from a blank slate - removes the single biggest reason businesses stay stuck on tools that are actively costing them time. Being able to import customer data directly, and export it again whenever you want, also matters for a quieter reason: it means you're never locked in. Your customer list is yours, wherever it lives.
The verdict
You shouldn't have to choose between "keep our history" and "stop using a spreadsheet." A decent import tool means you never actually had to.