We know that Satoshi's vision is one of Bitcoin as Money; nothing else.
From the "Bitcoin p2p e-cash paper":
Smart contract, smart property, autonomous agents, distributed markets will be a staple of the blockchain technology whether you like it or not
and sidechains are the ideal and arguably most natural way to implement these.The bold part is the only false part of that statement.
This is a classic example of the geeks trying to do too much at one time.
"The geeks fail to understand that which Satoshi hath created"-cypherdoc Had to tweak it a bit...
Argument: missing.
Show me a better way to implement fully decentralized smart platforms while also preserving the miners' potentially essential transactional revenues.
I know this is still theory at the moment but if the technology in the white paper can be safely implemented than I don't see a better technology on the market, at least presently.
Argument: missing.
Why is it assumed we need to implement fully decentralized smart platforms in the Bitcoin system?
Because Bitcoin is the one & only trusted ledger. If it isn't built within Bitcoin then you sacrifice trust.
Blockstream said it best :
Can't be evil no, he asked why we need these fully decentralized smart platforms in the first place? presumably for stocks, bonds, insur, contracts, etc.
No. Decentralized smart platforms can be used for a plethora of utilities some we don't even know about or can imagine yet.
His question was absolutely why we need these decentralized smart platforms to be within Bitcoin hence my answer.