100 % stake why still POW ?

Getblocktemplate in Console

version" : 6,
"previousblockhash" : "0000000007ef92c9463cc3556c6e97ddb61b55381564e89f3e3e850d644a5863",
"transactions" : [
],
"coinbaseaux" : {
"flags" : ""
},
"coinbasevalue" : 1500000000,
"target" : "00000000164e8300000000000000000000000000000000000000000000000000",
"mintime" : 1506912646,
"mutable" : [
"time",
"transactions",
"prevblock"
],
"noncerange" : "00000000ffffffff",
"sigoplimit" : 20000,
"sizelimit" : 1000000,
"curtime" : 1506912959,
"bits" : "1c164e83",
"height" : 171
}