CanBuildFrom got killed in 2.13, but taking a step back is exactly the right thing to do: The desire to return the same type of collection lead to overall slow

CanBuildFrom got killed in 2.13, but taking a step back is exactly the right thing to do: The desire to return the same type of collection lead to overall slow performance; it turned out it's a design dead-end that Scala is still suffering from. It should simply have been abolished and replaced, instead of applying some minimal fixes in 2.13 that preserved the wrong design choices.