It's actually neither, it's common sense, but thanks for calling me a liar or a moron.
If slicing is a net loss in credits then people will drop it. In order for it not to be a net loss then the price of the missions/schematics will have to go up. Pre-nerf if a slicer crits they got a nice lockbox and maybe a mission. The lockbox is the reward for the run and the mission is a bonus, and on most servers they are priced as such (slicers in my guild were just giving them to guildies because they sold for minimal amounts in the grand scheme of things).
Unfortunately there is a max that those missions are worth, based on their return in materials. Much like I am not going to send out 50 slicing missions to sell a reward for 500 credits, an intelligent player won't be paying 25k for a mission that will net them 10k in materials.
At the point in time where it costs more to get the rewards then the market will tolerate, people will drop. If folks like you want to "fill a void" by losing credits for no return then feel free, but most intelligent people will not. If the void being filled is the profitability of selling missions/schematics at extremely high prices, then you have proven my point.