True, although a navy blazer could arguably work for the latter situation and look just as good. Plus it can be worn indoors (can as in it looks right - there's of course nothing stopping you from keeping your peacoat worn indoors although that's a rather HK look).
When I was in uni, my "hops from home" garment was played by a barbour. Seems to be the thing in the UK, with a gilet added when extra cold.
I think the main issue I have with a peacoat versus a blazer is the former should be taken off indoors, exposing a sweater or shirt, which doesn't look quite as put together as a blazer over a sweater or shirt