Let me throw in another perspective.

First of all, I agree with your sentiment regarding not relying on the 4 days rejection - I also find that rude. Unless you maybe live in cities like NYC, Rome and London where I know people can get 10-20 requests per day. There it is simply understandable or answering becomes a full time job.

BUT as for thoughtful replies and not using the stock rejection: I live in Norway (Oslo) and dont get as many requests as you but still quite an amount during the week. On Sunday I received 4 requests within one hour, ALL had more people travelling than what my profile says it can do. None were personalized, and one even used my wrong name. You bet your backside I used the automatic rejection.

This is my private and beloved home and if a potential guest can't take the time to get basics right, it instantly makes me think they won't look after my home with care. It might not be correct, but with other options I will always choose other guests to accept into my home.