A *good* pilot could happily fly through cloud on the T&B in the event of an AH failure.
"Happily?" I realise you have inverted commas the good bit to make your point, but believe me it wouldn't matter how good you were. Any pilot would be in dead serious trouble if he lost the AH and had to fall back on the Turn Coordinator or the Turn and bank indicator. Unless of course he was current in the last few weeks on limited panel flying in IMC both in a real aircraft or synthetic trainer. Readers may recall from about ten years ago, a Mooney (?) flying near Mildura (?) at night lost his AH and decided to turn back towards Mildura and land. With only a Turn and Bank indicator he didn't last long and crashed after coming apart out of control.
Reminded me of a quiet event when a 150 hour student with his own Cirrus was practicing instrument flying in a synthetic trainer called, I think, an Elite flight trainer. The student was happily doing several practice holding patterns. The suggestion was made that it might be worthwhile practicing flying without an AH in case one night the AH fell over. The student said it would never happen in his EFIS Cirrus so no need to make it hard for himself.
After about the fifth holding pattern with the student congratulating himself how good he could fly on instruments, someone passing by the Elite trainer, quietly failed the AH. It took less than one minute before the student was in a screaming spiral dive cursing the poor old Elite trainer. Nothing wrong with the synthetic trainer apart from the failed AH. The problem was the cocky pilot. Even after that rather dramatic ending he still refused to practice limited panel on instruments. Last I heard of him was that he was a flying instructor teaching instrument flying...
