The original logic went something like this. The Church needs people to labor full time in service to the Lord. To work full-time in the Lord's service, a person must sacrifice earning a living at another job. Although the net result is the same as it would be if pastors were paid for doing the job of ministry, i.e., the pastor has an income and the pastor does ministry, their is a big difference in how both the pastor and the congregation understand the pastoral ministry. Churches do not hire a pastor to do such and such work in return for so much salary.
Churches call a pastor to be a resident holy person.
This compensation then frees the pastor to serve the Lord full time in prayer, study, visitation, sermon preparation, worship preparation, community service, and whatever else the Lord has in mind for the pastor. Pounding meant stocking the parsonage with all kind of food stores especially when a new pastor arrived. Many congregations view their pastor as a salaried employee hired to do the congregation's bidding. This mentality is further fueled when synod compensation guidelines encourage congregations to consider merit increases when determining the pastor's salary. If clergy pay is truly compensation then their can be no such things as merit increases.