You might be conflating the startup community with the open source community of the late nineties
Considering the large overlap between those two communities, I'm not sure it's an unwarranted conflation. The first tech boom included a bunch of Linux-oriented startups and IPOs, whose successful pitch to VCs involved essentially, "Microsoft is on its way out".
True, although a decent number of the web startups also thought Microsoft was the walking dead, because it had missed the web (which was sort of true, but ended up not killing MS).
Considering the large overlap between those two communities, I'm not sure it's an unwarranted conflation. The first tech boom included a bunch of Linux-oriented startups and IPOs, whose successful pitch to VCs involved essentially, "Microsoft is on its way out".