@matigo Interoperability with clients is unfortunately not as simple as digging in your heels. It depends on your line of work and your client's expectations.
Although most of the files I work with now are either cloud-based, or in a proprietary translation software format that has nothing to do with Microsoft, I do have some project management spreadsheets in Excel that require some complicated conditional formatting (no macros), which may or may not work in the cheaper alternatives. I do occasionally get work from clients that require editable MS Office files (Word/Excel/PowerPoint), and I would hate to give them a file that doesn't look right layout-wise.