Because investors have more money than sense and go where the buzzwords are.

The Decentralised idea of Web3 is largely the same processes that powered Web1, only with 3D advertising and more data collection.

You can have all the blockchains you want but you will still need to rent server space from a centralised provider and pay an ISP for web access. No amount of crypto investment is going to get rid of that making the idea of a truly decentralised web a myth.