"I don't like it so it shouldn't exist" ! I think this tutorial is very cool, I introduced programming and dapps to my 15 yo niece with it and she liked it.
It doesn't matter that I don't like it. Every addition to the blockchain imposes costs in storage, backup and transmission - forever. Nothing gets removed, so it just keeps growing. For property records that's a cost worth bearing (we had to record who owned what anyway). But how long and how much will it cost to forever record that Bob owned Kitty XYZ and then sold it to Allen? Multiply that by 50,000 other apps, and (millions?) of frivolous transactions. Just because we can doesn't mean we should.
It doesn't have to be like that. We could rely on periodic snapshots of the blockchain for future validation. We could even selectively include specific data in the snapshots to be preserved. Maybe some group might need to store the entire history of the blockchain but there is a lot of room for innovation to solve this scaling dilemma.