When you read this Ninth Circuit opinion, it seems so obviously right. How could the district court have gotten such a (relatively) simple thing as joinder so wrong? Obviously the various defendants were related. Or at least were related in the minimal way required by the federal rules. Or, even if they weren't, why weren't the improperly joined claims severed, rather than dismissed? Why was the district judge so harsh?
Reading between the lines, however, I think one might obtain a hint. It's an ADA claim about access to stores potentially brought by a high-volume filer who's looking to save on filing fees by dumping a number of different lawsuits into the same complaint. The district court probably didn't like that. It probably didn't like the merits much either. Hence the result.
The Ninth Circuit never mentions anything like that. But -- based on nothing but gut -- my money's on the district court not being at all fond of this type of litigation.