MS has done shady things but Netscape's own top employees have written about how Netscape destroyed itself with the version 4 rewrite. Joel Spolsky has also written about how complete rewrites are always a mistake.
Their corporate side failed too. If you weren't fortune 500, Netscape wouldn't talk to you. I was spending $50k a year with Netscape and they wouldn't fix a bug unless I paid for an additional $75k a year support tier. ( The bug was Netscape 4 didn't support dialing with area codes! )
Meanwhile during the late 90's Microsoft devs put their personal emails in the readme.txts and would quickly patch any bugs or add features if you emailed them.
All the small isp's (which were over 50% of the market) gave up on Netscape because of this.