How much of a pain was it when the vendor refused to fix your bug because it, or you, weren't important enough? When the vendor went out of business, or was bought by a company uninterested in the product you were using?
Oh, and when you consider writing a library internally, keep in mind that patents are a thing.
"It meant that developing libraries was actually a viable business."
Yeah, I remember that. I remember when there were a million billion little companies producing C++ libraries. Then C++ started to get really popular, and those companies' customers went from a small group of experts to a large group of, uh, non-experts. Then they discovered that support was hard and all went out of business.
I really wonder what would have happened it HP hadn't open-sourced the STL...
As a developer that was a bit of a pain since you had to get purchase approval instead of just adding a dependency to a build file.
But, I'm feeling that is actually the better model the industry should go back to. It meant that developing libraries was actually a viable business. Today companies just leech off the open source everything, externalizing all their costs and dumping the maintenance burden on unpaid volunteers.