Calling a big firm 小社, a capable child 愚息, or a careful draft 拙稿 can feel like false modesty. The guideline treats these as conventional word-contracts: you make “your side” small in language to show care — not because you literally believe it is worthless.
Same logic as serving food with 「お口に合うかどうか分かりませんが」 — not “this tastes bad,” but “I won’t force my judgment on you.” If that stance matches you, use it; if not, a frank 「おいしくできたと思います」 can also be considerate. Self-expression includes saying no to forms that feel fake on you.