Excel files can work surprisingly well in B2B scenarios where there's a high degree of trust. At a retailer I used to work at, we ran an impromptu Christmas gifts team in December each year, where corporate clients could put in a large order of gifts to be sent to their employees. Rather than build a website for it, we just sent them over an Excel file they could fill in with the name and address of each employee, the gift they wanted to receive and a message for the label. They'd send the file back to us and we had a process to validate the data and load it into our system. It sounds primitive, but it was much more time- and cost-efficient than faffing around with a custom application that we would only use for one month per year and which the clients probably wouldn't enjoy using anyway.