I don’t understand this view. Sure, they don’t need to criticize one aspect of a franchise when they praise another, but why shouldn’t they? Must praise and criticism remain always separate? If you feel DS9 is better in some respect to ENT, I don’t see any issue with you contrasting the two.
Steve Shives, for example, dislikes the second season of Picard, and in his review of a recent episode of Strange New Worlds, that was brought up. He praised the episode of SNW while criticizing the season of Picard. Is that so bad?
You may not be comfortable addressing that specific example, but in general, what is the issue with contrasting things one likes with things one doesn’t like within a single episode, a season, a series, a franchise, or pop culture at large?