Ultimately, Firefox loses when it loses the good things that make Firefox better than the competition. If Chrome (or any other browser) is doing something better than Chrome, by all means, copy it – or do it better. If you don’t know it is better, there is no “easy” choice to make (the risk may be minimal if the feature is not well liked or used by many people).
Is that what Chome users are thinking about when they demand exact feature copies? Is that what Mozilla is thinking about if they think copying features is easy?
Of course not. They are taking shortcuts. We all are.
It is easy to miss things if you aren’t looking for issues. There are no easy answers.