the newspaper article makes it clear that the SSR was in trouble, not the real radar
Whilst I know some who would claim that SSR isn't real radar in most places it is the main ATC radar and often the only ATC radar. Does anybody know whether there is Primary Radar in this area and if so was it also affected?
a bit strange that Mode S - ADS-B based flight surveillance info (provided by 'consumer product' class of hardware) was available, without AC appearing tenfold.
Not strange at all when you consider how they work. Both SSR and ADS-B have their weaknesses some of which are common to both. This set of circumstances exposed one of the weaknesses of SSR not present in ADS-B, there are other foreseeable failure modes which would only affect ADS-B.