Neither the definition of toxic, nor the definition of hierarchy imply any such relation, much less require it.
Hierarchies are what they are: an acknowledgement that the universe (and most subsets of it, e.g. companies, countries, etc.) is not a mere undifferentiated blob, but has qualitative and quantitative differences that we need to take into account.
You wouldn't get any arbitrary surgeon if you could have the best one, just because "hierarchies are toxic", right?
Hierarchies are what they are: an acknowledgement that the universe (and most subsets of it, e.g. companies, countries, etc.) is not a mere undifferentiated blob, but has qualitative and quantitative differences that we need to take into account.
You wouldn't get any arbitrary surgeon if you could have the best one, just because "hierarchies are toxic", right?