IMO complication is due to lack of good explanations and lack of understanding of the subject. Bitcoin’s PoW is complicated, the idea is simple but in practice you run into many insecurities (forks, confirmation time, lack of verifiable light client, rule of more work vs longest chain, 51% attacks and how to bootstrap a new chain, centralization of miners, etc.)

On the other hand the hotstuff protocol is much more easy to grasp IMO (check my explanation in the book Real-World Cryptography)

PS: oh and also Bitcoin proof of security seems like a nightmare. It’s nice to create protocols that look simple but if you can’t prove their security it’s a bit dumb :) on the other hand the safety proof of hotstuff is quite comprehensive : https://www.davidwong.fr/lbft_safety/