Two quotes from this Infoworld article about the SCO case:
“The OpenServer compiler is crap. Without (the GCC) they would be up the creek,” said Hans Anderson, the director of software development with Price Data Systems in Louisville, Kentucky.
The proprietary world would have created adequate alternatives to the GCC, had the free software not driven development tool companies out of that market, [Jay Davidow, a reseller with Winnipeg, Manitoba’s Profit Master Canada Inc] noted. “You had companies that made developer tools, but where are they today? They don’t exist.”