According to some reddit mems
"looks like one major advantage of stratis are sidechains in which dapps will run in - Also, the main chain will not run smart contracts, only side chains will. Each side chain however will lock up Strat and take it out of circulation.
so no bloating of the mainchain like in Ethereum. = better scalability"
im not an IT guy so i have no idea what does this scalability thing mean
Stratis Sidechains alpha incoming Q4 this year tho.