When does it make sense to use proprietary technology? Should you favor “enterprise” technologies over commodity alternatives?

Windows® is simultaneously an enterprise tool, a commodity and a consumer product. So are most printers. You cannot do without either because people want them or processes require them. But much hardware and software exists in distinct forms: (1) as enterprise ware only, (2) as commodity, or (3) as consumer alternatives - so you must choose.

When the choice is not dictated by people or processes, it makes more sense to use ad hoc commodity software, parts or equipment that can be vetted by the market and are less costly. When IT professionals spend fortunes on enterprise ware that fails, they do not publicize it in product reviews. Internet and Cloud companies however sometimes do (e.g.: Backblaze annual report of drive failures).  

In the Internet age and global economy, mass markets and volume drive innovation. As a result, commodity and consumer ware often overlap.

It is not by accident that Big Tech's server farms and much of the Internet economy are built on commodity parts and software. It is because this is what makes the most business sense. The information and communication sector and enterprises do not buy the same ware.

The key is to know what you really need and what works.

There needs to be an experienced technician, a process engineer, a buyer, a quality controller, and a psychologist in your IT manager or CIO.