Evolutionary rates vary among sites and across the phylogenetic tree 
(heterotachy). A recent analysis suggested that parsimony can be better than 
standard likelihood at recovering the true tree given heterotachy. The authors 
recommended that results from parsimony, which they consider to be 
nonparametric, be reported alongside likelihood results. They also proposed a 
mixture model, which was inconsistent but better than either parsimony or 
standard likelihood under heterotachy. We show that their main conclusion is 
limited to a special case for the type of model they study. Their mixture model 
was inconsistent because it was incorrectly implemented. A useful nonparametric 
model should perform well over a wide range of possible evolutionary models, but 
parsimony does not have this property. Likelihood-based methods are therefore 
the best way to deal with heterotachy.