"Comebacks Aren't Possible"
Is a thought on many players' minds. The general idea is that games are stomp or be stomped. It is a false one, but a widely accepted one nonetheless.
The fact of the matter is that people repeat the same mistakes in game and rather than adapt and own up to the mistakes they've made, they just keep on making them after personally admitting defeat on an internal level that reflects outwardly in their performance.
Games last anywhere from 20+ to 60+ minutes, a long duration in which people are allowed a window of opportunity to make up for their mistakes and move forward toward a possible victory.
Patience and observation are absolutely key toward winning. Timing is critical.
When an enemy gains a lead over a player, they must admit that they have been bested because of something THEY did wrong. Blaming the game, blaming the champions you face, blaming Riot, blaming allies...accomplishes NOTHING.
A player's first step toward recovering from a loss is admitting they messed up. Then they can identify what they did wrong. Then they can avoid repeating the mistake by doing something else.
Players must also respect their opponents as equal to or better than them. Players will often step up to the plate and automatically assume they can beat their opponents into submission without putting a great amount of effort into it. They underestimate their opponents and overestimate themselves. By failing to identify personal limits, and by refusing to respect their opponents, players fall into an endless cycle where they try the same failed method repeatedly and in absolute futility.
It isn't the game, it isn't the champions you pick or face, and it isn't Riot that makes YOUR games "unwinnable". You, the player, creates the unwinnable scenario by making the same mistake over and over and then letting that be the decider of the outcome.
Here's a personal example.
I was recently in top lane where I managed first blood, but my allied jungle forced a gank too early in my lane shortly after that. I was situated behind a minion wave and knew that neither of us would be able to secure the kill, but my jungle attempted it anyway. The enemy top did not die; instead, the enemy jungle came in and killed our jungle. I was forced back at half health. I had to return to base then walk back to lane as the enemy top surpassed me in level by 2. By fifteen in, the enemy top had almost three times my CS and had killed me once for attempting to farm. I spent a good portion of the game staying back. I couldn't even touch farm while the enemy top was there; so, I merely settled for soaking experience, biding my time for some opportunity. Whenever it arrived, I seized it by the gonads and either managed a kill or forced my enemy back. These opportunities were rare and few, but they were enough for me to recover from my early losses.
I was patient. I was observant. I avoided making the mistakes I made before so as to avoid giving the enemy any more of a lead than I already had.
I lost lane that game because of my early losses, but I did not let that defeat me. I managed to end the game with a very positive KDA, the best on my team, but that isn't saying much...
...We lost the match. It is a team game, after all and my team comprised of the following...
...The ADC who never killed a single enemy champion. The ADC and Support whose death total combined by end game exceeded a dozen. The jungle who failed more than half their ganks and continued to attempt to initiate fights against grouped enemies on their own. The mid lane assassin who managed some success, but proved ultimately useless by dying in over half their fights.
What I took from that game is this. Anyone can come back from a bad situation. I did it. But players have to exercise patience and better judgment. Players cannot simply give up at the first sign of trouble.
TL;DR
Unwinnable matches are made by the attitudes of players, not the game, not the enemy picks, and not Riot. Mistakes are accidents that happen, repeating mistakes are choices players make. Accept responsibility for your actions and decisions and improve upon them. Recognize your limits and respect your opponents. Exercise patience and observation.