> Why does this need a blockchain? Fon/BT has been sharing residential WiFi for years without blockchain

The difference is, as per the article, that the Japanese operator wants to re-imburse the WiFi hotspot subscriber. Something which is very much alien to BT's way of thinking.

Of course, whether blockchain is the right way do implement that aspect is a different question, and in terms of implementation I would agree that blockchain is un-necessary. But you know, blockchain bandwagon .....