Hey, I was in silver V and after a nerve wrecking 2-1 promotion series I came to Silver IV with 0 LP.
The first 2 games: 1 guy went afk and since we were only about even in laning phase we did not survive mid-latish game. The other game was just a their jungler out jungling ours bringing the entire teams moral down to rage and then leave the game.
Point is : At least give us a chance to fight against a demotion. It's really demoralizing to be demoted to a lower division and having to work your way back up to ANOTHER 3 game series checkpoint that is so shaky.
I know you can't just forgive a loss because it will not make things that much better (I support it though)
Suggestion: We shouldn't automatically be condemned for demotion because of 1 afk'er (or troll). If he goes leaves the game, at least split his ambient gold and make the gold obtained from assists worth more (to compensate for the last of 1 player). Playing a 4v5 should be reasonably winnable if your team is somewhat better than the other team (if you all win your lanes you should be given the chance for outside of the laning phase)
Another issue: There's too many divisions within a tier and it takes a ridiculous amount of games to climb up tiers. Winning (5)x(best 2 out of 3) is just plain cruel. You will need multiple tries to win your series, a climb back up again to try that series again without certainty of winning that series.
Suggestion : Obviously change the number of divisions per Tiers to 3 or 4. And if you are not gonna do that, make the players start at 50LP once they get promoted to the next division instead of starting at 0LP (grace period is not enough in my opinion because once you get demoted it takes a lot of games to get past the promotions again).