Yes in the `setop` current implementation, because this enables the script to be fast, short, and work with inputs without needing to call `sort`.
For comparison, a typical POSIX `uniq` implementation reads the input and solely compares two adjacent lines; this requires the input to be presorted.
An interesting upgrade could be to add a `setop` option flag that tells the script the inputs are already sorted and/or deduped. This can achieve the memory savings you're describing.
