I really hope you are right, but playing devil's advocate a little bit, some players also have an unused substitute clause which means they get a sum if they dont even appear. Some players in some cases I suspect have a higher unused sub fee than appearance fee, and therefore putting them for nominal minutes costs the club less.
Looking at ugbo for example (Potentially putting 2 and 2 together here and getting 5) A big money signing on a wave of good form, its not impossible that ugbo thought he should be playing so much there was a financial penalty to the club if he wasn't involved. In 9 league games so far, ugbo has come on in the last minute for 3 of them, Including this sat when we were 5 down and most of the crowd were already home.