I see their point, but this is exactly what I'm trying every day to prevent at work (at least to a certain degree). Way too many people use complex spreadsheets for business critical tasks where other tools are better suited.

If the concept of shareable libraries of function sheets become a reality, we're likely to end up in a scenario where corporate IT maintains one software suite, while the end-users supposed to use that suite ends up using a bunch of spreadsheets instead, but with no quality control and a backup/VCS resembling <filename>.backup.xlsx, <filename>.working.xlsx, <filename> (copy).xlsx, etc....