Well, let’s proceed in order:
1. There must always be a loser in this game.
MOBAs are zero-sum games, so one team must certainly lose. There is no draw, like in chess or football.
Exactly because MOBAs are zero-sum games, played in a controlled environment, every mistake your team makes, has a high likelihood to turn directly into an edge for your opponents.
This also happens to be the reason why people usually feel strongly about feeders, griefers, leavers, afk’ers and trolls: they’re hamstringing their own team, and giving a large edge to the other team, up to making the game unwinnable.
If your team has done everything perfectly or at least better than the other team, then it follows it has outplayed the other team at every step, and it should win.
If it loses, then the assumption is proven false and mistakes must’ve been done. Generally speaking, in MOBAs there is not the same kind of random events that can change the outcome of a match in the same fashion as what could happen in life or some other games.
On the luck-skill spectrum, MOBAs are almost entirely games of skill: the outcome is decided by how well those 10 players have done in that match.
2. You can make no mistakes and still lose
Actually, no. If another player is stronger than you, it’s because they’re making less mistakes. You can make no mistakes that you know of, but that’s very different from making no mistakes at all.
Additionally, if you were really playing so much better than everyone else (“no mistakes” assumption), then you should have been able to carry your team to victory.
3. You can still lose the game and have no idea why
Sure, but instead of going straight to blaming your team mates, watch the replay, and if you’re still not sure what you could’ve done better, ask someone who’s stronger than you to watch it.
4. Look at your game and figure out what mistakes you’ve made and what you could’ve done better
If you’re solo queueing, the match maker gives you four team mates, a process over which you have no control.
The only thing you have control over is your own game. Focus on that.
5. When is it time to take a break?
Whenever you lose your cool, your ability to look dispassionately at your own game, and just blame every defeat on your team mates.
This is among the best advice that can be given to a MOBA player, along with “Don’t effing die” long version: don’t die unless by dying you can seize a sizable advantage for your team; but this is advice reserved for those who are not only advanced enough to understand the notion of trades, but to efficiently and accurately assess trades while they’re playing.
If you keep blaming team mates for every loss, and take mental credit for each victory, then chances are you’ll never improve.
Worse, if you assume you’re always playing flawlessly and every defeat must be somebody else’s fault, then you’re going to get frustrated (the game then MUST be unfair, the odds stacked against you), which can turn into full tilt and then toxicity.
Which ultimately has been demonstrated to lead to extended loss streaks, more frustration, tilt and toxicity, and set off a downward spiral that ends with rage quitting, broken equipment and friendships, and more general nastiness.