Exodus 18:17-18 So Moses’ father-in-law said to him, “The thing that you do is not good. Both you and these people who are with you will surely wear yourselves out. For this thing is too much for you; you are not able to perform it by yourself.
When the ministry grows, there come a point when you might not be able to pray for all people. One of the reason for the use of anointing water and other mediums is that God is concerned about reaching his people to help them in times of need. It’s the anointing in the set man that makes what you received from Him work even in his absence. Things that Paul touched were able to heal people even in his absence. Acts 19:11-12 Now God worked unusual miracles by the hands of Paul, so that even handkerchiefs or aprons were brought from his body to the sick, and the diseases left them and the evil spirits went out of them.
Unfortunately you cannot make people see the power that is transferred for those who are like Thomas to believe. You cannot use science to understand the spiritual things. God is spirit, he can use anything to achieve his mission.