To be fair, Netscape lost because their product, at the time, was inferior. Netscape blew IE out of the water at first, but IE kept getting better. Netscape 3 was excellent, but when IE 4 came out, it was just better. Then came Netscape 4. 'Nuff said.

Lotus couldn't make the transition to Windows, and so lost to Excel (and perhaps Quattro Pro... it's been a long time and I don't remember details). This had nothing to do with copying APIs. Of course, it probably had everything to do with Microsoft's anti-competitive advantage by having access to Windows internals and undocumented features, but that's another matter.