Now realize when reading this suggestion, it is not going to 100% going to solve the problem. Trolls are going to troll and dumbasses are going to be dumbasses.
I think we all want the same thing here. We all want to play how we want when, we want right? the frustration and argument here is where to do that. Right now there just isn't a clearly specified place to do that. Add another mode/tier. Bots, casual, normal and ranked.
ranked stays the same obviously, ranked. serious play where you are expected to have a mid to high degree of gameplay competence. play to win. expect to be shit on for playing like a dumbass or off meta.
bots stays the same. very new players and vet players learning the mechanics of the game and/or new hero. play to learn, play for fun, play to faceroll bots to blow off steam, etc. anyone getting bent here is just trolling or a dumbass.
casual is where you go to practice against people and do fun/stupid shit like running full mage teams with no other items than boots. whatever floats your boat. players of any skill learning/playing against other people who are learning or dgaf about winning or losing. Gets rid of " wtf, get your shit together, stop feeding, etc" unless its a troll because everyone who joins understands this mode is for practicing and trying ridiculous stuff for fun.
normal is for non-30 or 30 players to play against other players to win. some skill required or you're probably going to get shit on, but all players trying to win and be competitive. this gives non-30 and players not wanting to play ranked a place to play competitively without that guy trying out if he can jungle a mage with a full potion build. Gets rid of the response "chill, its just normals" unless its just a troll because everyone who joins knows its a competitive mode and has the expectation to play as such.
like I said, this wont defeat trolls and dumbasses. you cant change that. however, there are clearly a few different opinions on what normals are or should be. so make clearly defined modes for all types of players, new/veteran, skilled/unskilled, play for fun/play to win, etc.