I have also been following this thread since the beginning and I join my thanks to Justme69 for very informative and correct information posted here.
The failure ( or more correctly unavailibility) of any warning system is not a problem per se. But fact is we all start to rely on them and reduce our alertness. Same for ATC with Short Term Conflict Alert (STCA). Everybody is supoposed to be able to work without one, but if you get used to it over many years, and suddenly ( and/or unknown to you) it is disabled, errors can turn into accidents. Ueberlingen comes to my mind of course.
Check and re-check and never asume .