How else do you propose to create a distributed concurrency?

The traditional approach would be a public ledger mantained by the 'miners' aka a block-chain. The the issue is that's not anonymous, but while a lot research went into creating an anonymous currency bitcoin was a MVP which took off. Now, I am not saying nothing about bitcoin was new, just the innovation was in the specific implementation not the overall idea.

Bit torrent was released in July 2001, bitcoin 2009 so the idea of distributed networks was fairly well established at the time.

PS: And yes, there was a lot of early criticism about the public nature of bitcoin.