There's a lot of truth in that. Which I guess is my real problem; people are so gullible. Maybe that's too harsh. Maybe they're just too lazy to bother thinking about value and price. BTD mentality, if you will.
I'm a proponent of voting with our wallets. If one company did something dastardly like shrinking the package size, and customers then started buying from the competitors who didn't, this whole shrinkflation thing would die immediately.
Instead we let them get away with it, so other companies jump on the bandwagon.
Consumers can have an effect. One product I buy regularly came out with a "New! Improved!" formulation. A quick comparison of the label showed that the "improvement" was a huge increase in the amount of water. What today we'd call "shitification." Customers like me wrote letters and stopped buying. Within a few months the company switched back to the "classic" formula, and sent me some coupons to get me to try it again. Hopefully they also fired the bean-counter who came up with that idea in the first place.