We do it anyway. It's easy enough to filter those types of emails. I think it's a huge plus for customer service to be able to say "Have a problem or question? Just reply..."
Sure. And I think that's a better approach, on balance.
How do you know if you've been filtered? Not getting a response would lead to a lot of frustration.
We only set really obvious filters, as to filter too little than too much. But of course, it's not perfect every time.
Having worked in email queues, filters are nowhere near good enough. Nothing is more infuriating than wasting hours on bounces.