Credits only come from two places: mobs and quests. If slicing 'gives you as much credits as killing a few mobs', then that's twice the mob killing credits. On top of the mission credits.
Just to do the numbers:
if 30% of the server population has only slicing as a gathering skill, and only runs lockbox missions, instead of a random other gathering profession and running the corresponding gathering missions (and putting the mats on the market):
Let us assume a slicer's credit creation (credits created, not traded) increases by 30%
This 30% is easily attainable with both gathering credits and slicing missions.
The credit destruction from sending the companions on gathering missions decreases by 100% (since the cost of missions is already deduced from credit creation). Lets say this would otherwise consume 15% of your credit creation.
Based on these numbers, the slicer creates 52% more credits than the gatherer.
Globally the slicers now increase monetary supply by 15%
The market also has 30% less crafting materials. Not having tons of time to research the shape of the demand curve, let's assume this increases material prices by 20%.
15% more credits and 20% more costly materials, crafting materials now cost 38% more. To a pure consumer, who gets nothing from the 15% inflation, buying crafted items costs 38% more, and buying anything else on the market costs 15% more.
Not that I care... after all this is a video GAME. But slicing still sucks, since it's the only tradeskill that makes the game worse for hyper-casual players.