I'd never use silicone, etc. where a gasket could be used unless it was the exhaust gaskets with headers. Even then, I run soft copper gaskets there and Stage 8 locking SS bolts w/o any issues. Yes, the china walls alway get high temp silicone too but that's it.
Using silicone to coat gaskets in many places (water pump, t-stat, fuel pump, etc.) is something I do on occasion too. But having seen the disasters of fellows who use silicone like water, jamming up oil passages or leaving pieces behind after yanking say an intake....it's bad news inside any engine.