That link explains a mode by which Spotify's cloud based music can be available offline. iTunes Match gives access to YOUR OWN music via the cloud. Do you not see the difference?

I have 15,000 songs in my iTunes library, the vast majority of which are not on Spotify. My 16GB iPhone would normally only hold a fraction of my music but with an iTunes Match subscription I have access to it all.

Also, it gives an off-site back up of every matched song. So tell me, how is iTunes Match similar to Spotify?