unfortunately what it comes down to is the fact that the high elo players were probably in a party with one of the lower ranked players or it was 2 different parties with the lower ranked players. the same kinda goes with the level 30's on your team they were probably partied up with the sub 30 players.
The kicker is that most people will say let it slide it is just a normal get over it ect ect ect but the fact is that "normal games" matchmaking does not really look at what rank you are in solo/duo queue it basically takes the summoner levels and tries to even it out.
Unfortunately you got a raw deal from this and i can say that i have also experienced this when playing with friends who are not level 30, one game apart from 1 sub level 30 the lowest rank of opposition was a gold 3 and highest being a diamond 2 whereas my team comprised of unranked, and bronze/low silver players. This has also been going on for years and nothing has been done about it and probably wont.
The general point that will come across from many of the members here is get over it move on it wont happen often ect ect ect but i know how annoying and frustrating it can be and really a waste of your time.
so much for ritos statement of "Matchmaking will give both sides an even chance of winning"