PHP works fine. COBOL works fine.
Nobody ever said Rails doesn't work. Or doesn't work fine. That's a straw man.
It's just that Rails, and Ruby in general, is in clear decline. Not just because some new flavor of the month frameworks are coming out, but because a lot of the concepts Rails supports are antiquated, and Rails hasn't shown to be that adaptable to more modern front end trends after years of efforts from DHH.
Hell, I'm sure that even DHH himself would be very upset if people settled for something that "works just fine". He's just not happy that this time around, that characterization is being used to describe his creation.