You can be sure that losing to a smurf will be followed sooner or later by winning thanks to a smurf. That happened to me often, im playing mid and usually win my lane but sometimes there are some low level steam acc rampager guys securing their ranged creeps, farming faster and/or ganking better as i do. It happens, its normal. I had this yesterday, but the next match there was a morph Pos 1 who absolutely stomped the enemy team solo. I could have been afk the whole match.
What i want to say is: If you are hardstuck at your rank for hundreds of matches or weeks or months, hell even years…its not about smurfs or "bad team"….its only you.
It took me one year to realize that there is no "forced fifty". BUT, there is an algorithm which matches you against better players while giving you some trash. Thats the test if you really belong to the higher bracket. It usually happens at the edge of lets say Crusader 5 to Archon I, Herald 5 to Guardian I, and so on.
gl hf, stay calm and chill, its just a game.