As it has been noted many times having alternate accounts is officially not a rules violation, but throwing or boosting is.
That being said, I personally will agree that having alternate accounts (especially on console) is causing more disruption and I do feel Blizzard should revisit their overall policies to how they handle disruptive behavior overall when it comes to alternate accounts. (I even talked about this in a video yesterday.)
I myself also see problems with alternate accounts on the PC platform both in my own games and in other games that I have watched on Twitch. Stunts from popular streamers like “Drunk Unranked to GM” challenges are showing up and I think they are disruptive to innocent players trying to do their best at various ranks.
The problem of course is how does anyone properly handle or restrict players from having more than one account. Some countries like Korea have rules and laws that help enforce this, but this is not so easy for western markets.