RE: "Download Blockchain" Button
You are trying to solve a problem that is not there or already solved.
I guess you also have to re-think that "downloading" the steem DB (or the BTC blocks) pre-verified via a torrent exactly is NOT decentralization.
Many blockchains offer the a pre-verified blocks db snapshot via https/torrent/rsync/ftp for convenience, but if you did not sync the blocks yourself, you have to trust the source of this snapshot to give you a geniune one.
On the other hand, syncing from multiple peers starting at genesis, you can be sure to have a clean and trustworthy blocks database, because your own node applied consensus verification on all blocks itself.
Syncing/requesting blocks from multiple peers is fast and decentralized, most blockchains implement a DHT for that. So "syncing" is like torrent - but better.