They are the ones we read about in the accident pages
No we don't. IFR accidents involvng IMCr holders are almost non-existant in the accident record. I've read zillions of web postings conjecturing the dangers of the IMCr and never seen any evidence for it. It's been around a long time and enough people have held it that there would be an accident record to support the "inadequately trained, don't stay current, blunder on regardless" hypothesis if it were true IMHO.
I'm not saying the IMCR danger hypothesis is impossible. But every Licence, Rating, Privilege etc has a potential danger scenario of being used to its legal max limit with legal min currency (or illegally in your French example). There's no evidence that such a danger is any higher with the IMCr than with any other qualification. It seems to me the training, privileges and how pilots use those privileges all line up very nicely.
brgds
421C