No need" is ambiguous.

The words “Not necessary.” are ambiguous. When “condition X is not necessary to achieve objective Y

• There is at least one case where Y is achieved even if condition X is not satisfied.
  • logical
  • X is not a requirement.”
• For the difference D between Y when condition X is not satisfied and Y’ when it is satisfied
  • D is zero.
    • This is a stronger argument than “X is not a necessary condition” above
    • Concept similar to “whether there is a significant difference” in science
  • D is not zero, but small compared to the cost of acquiring condition X - [Profitability Criteria
  • D is not zero, but the difference is not valued by the speaker.
    • Speaker’s subjective value criteria

There are two extremes, “X is necessary” and “X should not be there,” and everything in between those two extremes is vaguely called “X is not necessary.”

This page is auto-translated from /nishio/「必要ない」は曖昧 using DeepL. If you looks something interesting but the auto-translated English is not good enough to understand it, feel free to let me know at @nishio_en. I’m very happy to spread my thought to non-Japanese readers.