Answer
The problem with putting all "protists" in one clade is that they are only distantly related to one another. In fact, some members of "Protista" are more related to other kingdoms than they are to one another. Modern analysis has identified at least five separate clades of "protists" that only have a distant relationship with one another.
Work Step by Step
The problem with putting all "protists" in one clade is that they are only distantly related to one another. In fact, some members of "Protista" are more related to other kingdoms than they are to one another. Modern analysis has identified at least five separate clades of "protists" that only have a distant relationship with one another.