Basically title.
I know a lot of people here would like to play fairly and all but accounts are way too cheap in Dota 2. You can buy a 1K MMR account for like 10€.
As a 7K player there isn't much to do. I experience smurfs 1v9'ing the games, too. You either need to learn how to ignore your emotions in some of your games and just accept things as they are or you can look to play another game, or another hobby.
I don't want to sound rude but in my eyes smurfing will never stop. I'm level 5 on FACEIT(CSGO) and I see just as many smurfs there as I do in Dota 2. Besides smurfing has been a problem in every multiplayer game known to man.
So yeah, it's been 10 years of Dota 2, if not more and smurfing has been an issue for the majority of the time — so you better find a way to enjoy this game other than complaining about smurfs or you're just better off doing something else, honestly.
Source: https://www.reddit.com/r/DotA2/comments/vi3odi/unpopular_opinion_smurfing_will_never_ever_stop/