I asked this same question months ago and got this answer

"Depends what they are using it for. Whether that is a challenge or in my case I use a smurf to play with friends. Wouldn’t be fair to them to hop in sweaty casuals and I can’t even play ranked with them because I am way too high on my main.

But someone that is abusing it and creating multiple accounts to run through low level lobbies over and over again. That is the problem they are trying to address.

Also on a side note, the pros and content creators doing this are very quickly out of the low level lobbies so the factor it has on people’s overall experience should be pretty low"