Personal opinion:
If you feel annoyed by such warning then you are trying to post AFAP and not trying to add new value to the topic you are trying to respond to.
Reading above comment, which was posted while you are writing a response, will help you improve the quality of the responses, and therefore disabling this feature is not a good thing.
I agree with you, and the warning feature should be very useful for adding a lot of value to post quality. By default it really doesn't matter to me, and so far I've never disabled it even after almost 7 years. But maybe, it just depends on the habits of each user and the forum provides that feature for them.
Instead of thinking about this feature, I tend to think how to ask the admin to enable email notification when one topic is deleted. In the last week, 2 of my posts were also deleted in one topic that probably has more than 1 page, of course not an issue with the deletion, but I just wanted to get notification that the topic and all posts were deleted.
I could recall I had once disabled this warning and I didn’t like it that much. When a new topic is created(mostly question like posts) you will like to get it answered and in the process someone might have done which at times look almost similar to my own suggestions. Without the warning I end up posting a similar answer which is regarded as spamming to me. So personal I feel it’s safer leaving the warning enabled to avoid cases of my kind.
Concerning the post delete notification some members have requested for same but I think it won’t be easier since there might be lots of posts once a particular thread is deleted. Just like you said a post of more than a page was deleted that automatically means close to or more than 20 post which in turns mean 20+ members might need to be notified. But it’s frustrating seem posts been deleted with notification
