> Supposing that the advice it provides does more good than harm

That unsubstantiated supposition is doing a lot of heavy lifting and that’s a dangerous and unproductive way to frame the argument.

I’ll make a purposefully exaggerated example. Say a school wants to add cyanide to every meal and defends the decision with “supposing it helps students concentrate and be quieter in the classroom, why not?”. See the problem? The supposition is wrong and the suggestion is dangerous, but by framing it as “supposing” with a made up positive outcome, we make it sound non-threatening and reasonable.

Or for a more realistic example, “suppose drinking bleach could cure COVID-19”.

First understand if the idea has the potential to do the thing, only then (with considerably more context) consider if it’s worth implementing.