**lets hazard a guess as to the intention of the prophet pbuh. i think its to point out the importance of the sura and the message contained. it doesnt nullify the quran or umra etc. like the gateway to islam is the kalimah, tauheed and belief in the last prophet, but islam is much more right.
what abt our intentions? is sawab really important? how many other daily life actions nullify that sawab? remember the story of hazrat rabia basri ra, she wanted to quench the hell fire and burn the heaven so that people wud love n follow allahs will without fear of heaven or the wish for jannat.**