My time is valuable.
"but successful attacks would need to have a larger effect on loyalty, since they would by necessity occur less frequently?"
The answer is no.
With scouts, it takes around 3 hours to bring down the loyalty from someone thats a few tiles away. Then I sleep and wake up the next morning to finish it off. With the current mechanics its still quite a chore.
Without scouts, you'll literally be babysitting your attacks for several hours. It gets exponentially worse the further away your target is.
People who use the scout trick still invest quite a bit of time and logistical management to do it, but because the results are interesting and worthwhile they're willing to do it.
It seems that the people who are really rallying for removing the scout trick are afraid to lose cities and want to remain there forever. The fear of losing a city stems from the time lost in investing in building up the cities resources.
Clearly time is the greatest asset in this game. The scout trick allows players to do interesting things with the least babysitting.
Babysitting is bad. Playing is good.
If you can think of an alternative proposal, it has to involve reducing waiting time for it to be fun. You argue the defense of a city is what your concerned about, then maybe defense mechanics should change so that its harder to siege a player city. Keep the ability to scout spam but make the initial destruction of the resident army more difficult.

