Yes, the garbage excuse of "I have more models therefore my reinforcement cost should be cheaper". People who think 6 models is worse than 4 are players who think models dying is only determined by RA
If 2 squads have equal cost of getting a squad, then yes, the one with more models will have lower reinforcement. More expensive squad with more models will also have lower cost.
No, its not garbage excuse, its mathematical fact that people who aren't friends with numbers are unable to beat into their own thick skulls.
No matter how you try to spin and twist it, reinforcement costs are fair and round to ~40% of squads total cost to fully reinforce from 1 model.