H. W. Fowler

Fowler named “elegant variation” — the habit of reaching for a synonym to avoid repeating a word — and judged it a fault, not a virtue, when clarity is the goal. Swapping synonyms to sound less repetitive forces the reader to decide whether the new word means something new. In persuasive copy that doubt is expensive. Lens cites Fowler as the long-standing usage authority for keeping one word per concept: vary your verbs, but keep one word for the concept you're selling.