Oil spray, FF, etc. do make a mess and require re-application every year or so. But they are relatively cheap to apply (very cheap if for DIY) and can be easily touched up in problematic areas with just a spray can. But if done properly and re-applied periodically, they work as advertised.
For people having the means and equipment to try out the more expensive products, more power to them, but for the average user, oil spray works the same. And if my mechanic complained about getting dirty, that would be the last time I used his services. Myself, I don't mind getting dirty, and it's only few jobs where I have to touch the treated components. Maintenance wise, brakes, oil etc., I don't get dirty from the coating at all.