The Foundation sees this as a contradiction to the EU’s own interoperability goals. Although XLSX is standardized as OOXML according to ISO/IEC 29500, Microsoft’s implementations often deviate from the specifications. Furthermore, features often change undocumented, which complicates compatibility with open-source software such as LibreOffice.
Unrelated anecdote, my brother’s then wife post a picture of them on Facebook. Our aunt saw it, took a picture of her monitor with her phone, went to the store to have them print the photo out on photo paper, and then mailed it to my brother.
So he got his original photo back, but at a greatly reduced quality and with monitor glare added!