Well, you might also look at it in this sense: the elves had their stuff (loved ones, countries, personal possessions, etc.) and their numbers didn't grow like men's did. So they might just want to defend all of it personally. Whereas men could be pretty sure that even though it was honourable and their duty to defend their stuff there were so many "other guys" to do the dirty work that it might not be necessary to fight.
Besides, who does?
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'It just shows you how true it is that one-half the world doesn't knows how the other three-quarters lives.'
Bertie, The Code of the Woosters, by P. G. Wodewouse