I don't care about my win/loss record, in part because I'm not a real competitive person...but also, my reputation and how other skilled players perceive me is independent of my win/loss record...people online know that I'm competent and skilled but hardly a pro....
But, that's for skilled 5s games...what if I wanted to join a random 2v2v2 or 6 man ffa? Not all those people are regular players in the 5s and thus won't necessarily know me...they are going to judge me by my win/loss ratio and so it helps if my win/loss ratio is inflated or deflated....
Additionally, newer people that don't have a reputation from diplomacy or from the forums bank on their win/loss record as proof of their skill/competency...
So, while I "don't care" about my win/loss record, I (and others) do like getting the win when it really was a win, because accurate records (however unrealistic) would be nice to have....
It is a strange issue for me, I don't really care for that ratio either (but it looks nice if i have more win than losses, i feel better for some reason), BUT, if i get the win i deserve, it makes the match completed for me, it feels bad to just leave a game before the last hero leaves, and it makes it spoiled for me, feel incompleted, like a film i don't watch till the last minute and leave before the actual ending even the main battle was done some minutes before. And I am like that newish player who is rated from his winloss ratio as I am not well known in skilled games, and I don't really have much time for playing online for an unfortunate reason, thus it is always a reason to get the win if I did everything for it. (it is a different question when i get almost destroyed and still my team wins it doesnt feel good, and that win means much less for me as i couldn't really accomplish anything to achieve that victory, big merit holding my last planet.. I know it still adds to victory but feeling no chance to do anything really helpful almost whole game doesn't feel that good like I was able to destroy my opponent).
Oh and I am that kind of person who doesn't have that much time to play a day, and as i would like to get my win and someone drags the game for an hour i get really upset, I don't like my day ruined by someone who thinks he is that funny and i will not be able to play even a smaller 2v2 game after that game (I don't really like 1v1-s as my skill is like its hard to find someone who stands a chance against me and i stand a real chance against him..)