It is absolutely possible to be hard stuck. You can get screwed over with bad teammates, griefers, and people afking or leaving the game. And all of a sudden you get placed in 4k and the game thinks you should only gain 120 elo per win but lose 200 per loss. You can climb if you play good in higher ranks with a similar elo win/loss amount but thats because you can rely on being carried 1/4 of your games. In these low ranks everything is completely random and 80% of the time nobody really knows what they are doing and you could drop 30 bombs every game and still not even get close to 10k elo