Why did Buddha use the 'Raft Simile'?

The Raft Simile says, in part: > I have taught the Dhamma compared to a raft, for the purpose of crossing over, not for the purpose of holding onto. Understanding the Dhamma as taught compared to a raft, you should let go even of Dhammas, to say nothing of non-Dhammas. [[MN 22](https://accesstoinsight.org/tipitaka/mn/mn.022.than.html)] Why did Buddha use the 'Raft Simile'?