It did not. Free software did. The term "open source" was coined by Christine Peterson at a meeting in January of 1998, as Netscape was contemplating releasing their source code as free software. The Open Source Initiative was founded a month later, and forked the Debian Free Software Guidelines, written by one of the OSI founders, Bruce Perens. This was a deliberate marketing exercise, both to avoid the unfortunate "as in beer" connotations of free software, and to distance the concept from the FSF and Richard Stallman.
In 1998 there definitely weren't millions of open source projects. Debian 1.3.1 (released in 1997[0]) had over two thousand packages. I pick Debian here because they only packaged software with unambiguously Open licenses. That's just packages shipped by Debian and not a full accounting of all open source software packages available in 1997. I'm sure some Walnut Creek CDs had a bunch more tarballs with more ambiguous licensing.
Open source software existed before 1998. I don't know why you're trying to quibble about the exact branding, just because the Open Source Software term wasn't coined until a certain date doesn't mean that is the start of all software with open licenses or people publicly releasing the source of their software. The GPL, MIT, and BSD licenses are all from the 80s.
It did not. Free software did. The term "open source" was coined by Christine Peterson at a meeting in January of 1998, as Netscape was contemplating releasing their source code as free software. The Open Source Initiative was founded a month later, and forked the Debian Free Software Guidelines, written by one of the OSI founders, Bruce Perens. This was a deliberate marketing exercise, both to avoid the unfortunate "as in beer" connotations of free software, and to distance the concept from the FSF and Richard Stallman.
All of this is well documented.