There are, unfortunately, some few who would abuse the system by repeatedly using the "Alert a moderator to this post" function; the delay is one way of preventing this. Ten seconds is not much of a wait IMO, and if there are several posts that need moderator attention just mention that in the "AMP" message.

When you report a spammer, we have tools by which we can mass delete all the spammer's posts as we handle the spammer, so there's no need to report each one.