There is nothing wrong with having an irrelevant share of the market. Most software I use has a market share in the 0-2% range.

However, Mozilla screwed up quite badly because their response to being pushed out of the mainstream was to gut everything that would have made them an interesting niche player. Their niche could have been "OK, this isn't Chrome but you get an IRC client and a bunch of crazy capabilities that are fun at lan parties. We'll train the next generation of devs by giving them cool capabilities to experiment with!". Instead, the niche is the worse version of Chrome.

> metrics have shown over and over again that people didn't use XUL addons

Now the metrics show people don't use Firefox. Funny thing, life. I think it was a bad time to make a metric-driven decision.