I can tell you from personal experience, that if you have a warming fire, you don't need a blanket at all, although a reflector of some sort comes in handy. Above timberline and in similar places, warming fires are hard to come by.

It is quite true that sleeping bags, generally constructed with nylon cloth or similar, don't go well with the sparks and embers generated by a fire.

My personal view is that an open fire, other than for emergencies, is an environmental no-no and all too often an accident waiting to happen. This varies a bit depending upon the location.