Steemify doesn’t ask you Coz you need only notifications from them, but if you click on the post ( subject of notification) , and try to edit something or vote or any ( they will ask you to log in with your private key too .
Notification vs posting or voting options is the key difference between steem dapps that ask for keys. But generally as @exyle said above steemconnect is made to be safe ( and will encrypt your keys before steem dapps connect to you.
However, not all dapps are safe 100% .. dapps will not have your key but have the permission already to do what is to be done by a key.
So, better to power up most of your steem assets.. leaving very little steem or SBD not powered.. and never use your master key .. use posting or by far active key.. so if something wrong happened, hacking you account so to say, hacker needs long weeks to power down ( and will not be able to withdraw) .. meanwhile you would use your master key to log in and change it which will immediately change all your other keys and hacker cannot steel your funds.
That’s to the best of my knowledge .. and I wish if something wrong anyone to enlighten us more !
Cheers 🥂
@milano1113