Originally Posted by Philip M
While many people are still using older browsers, it is pointless to code in such a way that it works only in browsers which support HTML5. In a few year's time - perhaps.
Anyway the wording of this particular question is such that it probably originated as one intended to find out whether the person recognised that the filter method is the solution to such problems - what the problem asks you to do matches so closely to what the filter function is designed to do that it makes no sense to use the problem for anything else other than to test if the person knows about filter. Using the problem that way would make any answer that doesn't use filter wrong.
I mostly agree with you about execution speed. Readability of the code so as to make it easier to maintain is far more important and will save far more time than using more convoluted code that results in a minor speed increase. Where there are two alternatives for coding that are equally readable and where one is faster than the other then it makes sense to choose the faster alternative as the way you write your code. Where the faster version also results in shorter and more readable code then that becomes the obvious choice.