Blizzard never paid good attention to community issues, including toxic behavior. They simply disregard it. They might temporarily ban extreme cases, but the overall toxicity in pugs never is a problem in their eyes.
Add to this “difficulty and pugs don’t go well together”, then add “timed runs and pugs”…and we get the current M+ pug situation.
I personally avoid M+ for this reason. Joining a community doesn’t work in all situations, for example when a person’s playing hours are different than other community members.
Pugs should be a way to finish a task fast and without frustration, albeit on the expense of lower difficulty and lower rewards. An esport activity really doesn’t fit here.
I think it’s laziness from Blizzard’s side, unwillingness to fully comprehend the situation.