Splatfests make sense as a timed thing/special event.
Maps and ranked modes rotating also makes sense to prevent people from just dodging certain maps and games as is common in shooters.
But fucking limiting when you can do Salmon Run? What in the fuck is Nintendo's logic there? I guess I haven't really paid attention as I'm not a fan of horde modes and don't care about it anyways, but if people want to do it let them do it whenever wherever. There is no point in it being limited.