The fact that mixers and their representatives will just disappear when they shut down is understandable, but not while you're still in business.
If someone stays in the business, then that is more reason to close all connections with the previous mixer business.
For example, if the Frogmixer owner has ever compromised personal data with this service, even if it was paying for domains via PP or bank card, he will certainly not allow a new business (mixer or something else) to have a connection with it.
The Samurai case is something that is a big warning to everyone, and one of the most obvious reactions is Wasabi's disabling Coinjoin functionality.
Although I would like to know the real reasons for the closure of some mixers (even those that enjoyed a certain reputation), I cannot blame them for leaving without saying goodbye.