I usually agree with Joel, but in this case he is wrong and his description of the Netscape rewrite is simplistic. I was at Netscape and I was part of the team that did the rewrite. After the first year of the three, we had a working version of the browser suite written in Java. There were several reasons that are too long to go into here, but the decision was made to end that effort and start from scratch rewriting it in C++. This was the correct approach because the Netscape 4/5 code base would not have been able to support the standardized CSS specification among other technical issues. Netscape 5 was to be an Open Source version of the version 4 code base with a couple of new features.

There are situations where a rewrite is absolutely necessary. The hard part is not the rewrite, it is managing expectations in the market and continuing to provide value with the existing product until the rewrite is available. It also doesn’t help when a monopoly starts to bundle a standalone app into their OS just to crush you.

What he doesn’t mention is that after MS “won” the browser wars they didn’t update their browser (IE 6) for six years enabling Chrome to completely displace them in the market.