Stating that two things share a trait equally does not always achieve the usual rhetorical effect of a simile. In ordinary simile, a more familiar or clearer comparator helps explain the subject.
Saying “Two people are the same height” is an ordinary comparison. Describing one as “tall like a palm tree” supplies a visual standard.
Yet special aims, reversed simile, or imaginative novelty can make comparisons effective even without a simple hierarchy. Logical validity and rhetorical force are separate questions.