Fortunately for you, you had a good experience. This is not generally the case anymore. Even in ARAM and Normals the trolls are heavy, they toxicity is thick. I'm glad you made some friends. My question would be did you win that first game. More often then not it's the players that think they are good and a person has a bad game or a rough start that starts the toxic frenzy. I'm glad you had fun, love seeing that some people can realize it's a game, and not an EP measuring contest and being toxic causes far more losses then wins. Glad you met some nice people, but I have to reject your point on the community is improving, really, it just seems to be getting worse.
Mute buttons are great, and as Limmie said, unfortunately the only safe way to play and have fun is to mute your entire team anymore, but I do feel if more people spoke out against the trolls, and toxic asshats out there then (and reported them also) we might actually see some attitudes change. I don't care if 3/4 the community quit that are toxic, people who leave the game and don't say anything just don't want to be around the toxic environment, still would outnumber them in long run. Plus if there is no home for the "Trolls" because people don't tolerate it, then they would move on also
Glad you had a good experience and made some new friends though.