I dunno what the alternative is, but there's enough people who've smurfed their way up the ladder to suggest it's not exactly uncommon.
I am unsure how viable it is, but it wouldn't hurt my feelings to see them find some way to kick bonus points back into your wins.
Say you win two, or three, or whatever number you want to say in a row...kick me back some bonus points that I no longer receive because my placement is shot. Give me the opportunity to earn those points over the next 10 games or something, so that when I win I actually gain more than I lose again and am more likely to move forward.
I mean, realistically, if they didn't want to do more regular resets (or individual resets more specifically), you could allow an individual the opportunity to regain the ability to gain bonus points for "x" games once every few months.
The bonus points are the difference between people getting a decent rank and people having a shitty one and having to grind it out. And probably a decent chunk of users just getting pissed and quitting outright cause of the teammates they see in a bracket they eventually outpace in knowledge/skill but can't surpass in MMR due to 80 points for a win and 120 for a loss.
I am 40-38 on my second smurf. Straight to rank 1 with it because I started out 13-2 in the previous season before reset, so after placement it put me at rank 6. From there you just have to break even with bonus points and you fall upward into rank 1. On my main I am 130-85. That account was once trapped at rank 27, It took me 115 games to get rank 1...with the smurf it took about 30 this season (counting placement in those games). Even with the vastly higher winrate, my main account was hosed. That's kind of broken.
The other alternative is to remove bonus points altogether so that everyone has to grind it just like in Hearthstone, but it would be very messy in the start with superior players playing through lower ranks/brackets. They could bonus rank you up with each new season in a similar way, though.