[singleuse]

It doesn't mean the product was actually good, it simply means it lacked a better alternative.

[tomkarlo]

If a product manages to be better than all the alternatives, it's hard to argue it's not a good product. At the very least it had to be better than "whatever everyone was using before" and "not using anything."

[nitrogen]

For the first few years, there were lots of sites that were designed for IE that broke in Firefox. Thus, at first, it was actually worse for many people. Yet, because the early adopters kept pushing it on everyone of their malware-ridden friends and relatives, it grew in usage anyway, allowing Mozilla to afford to make it better.