It's common in multiplayer games to blame your teammates for your losses. I am saying that if they have equal trophy count then you are not as good as you think you are. Yes, they might make mistakes. So do you. The matchmaking system has determined you two are equally skillful. Perhaps they make mistakes obvious to you, and perhaps you make mistakes that are obvious to them.

You're right that the more experience you get the better it is for you in terms of brawler vs brawler matchups, but that becomes a moot point if the player has been able to climb the ladder despite their inexperience. What they lack in experience in some areas they have clearly made up for in skill on other areas.

Iow, focus on yourself. And if randoms bother you do much consider playing in teams. But then you'll need something else you blame your losses on. Best of luck.