Okay so what you're saying is people don't have 3-9 hours to burn? Just to let you know there are people who actually do and for the right reasons they might spend that time FC'ing. If you consider that a lot of people buy a place in FC parties and charge 100k per hour which is entirely possible, you could make ~18 mil in 10 hours which would pay for 1/3-1/4 of a relic stage 4 or 5, in 1 day! I think that's a good reason to spend 10 hours doing the same boring thing over and over.
Also just to add, people might have friends that want to help, and for a cut of the profits might join in the FC to take over after 4-5 hours giving you time to rest so although you're advertising for 10 hours, you're not actually cleaving for the whole 10 hours.
It is hard for SE to differentiate between RMT and genuine players without a few "casualties" but FC'ing is fine imo, and if people are willing to pay for it there shouldn't be anything wrong with it. I don't personally sell FC services before you say anything, simply because I'm not the sort of person who could do the same old thing for so many hours even if I do get paid, but some people would and I agree with their reasons and they shouldn't be classed as RMT.