It is. But if a provider is not taking junk mail seriously, what is the alternative?
There is a limit to have much effort the receiving network can be expected put into filtering yahoo ham from the yahoo spam, and a limit to even how possible it is to reliably perform that filtering. Just expecting your users to put up with the influx of junk you can't filter (without too many false positives) and putting up with the processing load of attempts to filter it, are not valid options beyond a certain point. Yahoo knew they were a problem for some time before others started blocking mail from them en-mass and did nothing, or at least nothing useful, to fix it at their end despite warnings.
Also, “choice of email provider” is not a protected class in any jurisdiction that I know of.
There is a limit to have much effort the receiving network can be expected put into filtering yahoo ham from the yahoo spam, and a limit to even how possible it is to reliably perform that filtering. Just expecting your users to put up with the influx of junk you can't filter (without too many false positives) and putting up with the processing load of attempts to filter it, are not valid options beyond a certain point. Yahoo knew they were a problem for some time before others started blocking mail from them en-mass and did nothing, or at least nothing useful, to fix it at their end despite warnings.
Also, “choice of email provider” is not a protected class in any jurisdiction that I know of.