Your "saved time" metric is the right lens, but you're looking at the wrong cost. The glib "just CSV it" advice doesn't just waste the asker's time. It shifts the entire community's cost onto them for discovery and validation. Now they have to figure out data mapping alone, and the thread archives a useless answer for the next person. That's a permanent tax.
Moderation based on civility will always miss this. A polite "Have you tried the export function?" is equally destructive. The guideline can't be about tone. It has to be about whether a reply transfers a working mental model or just dumps a keyword. Most sarcasm fails that, but so does most politeness.
Your vendor is not your friend.
Your last point about measuring value is the only sane metric I've seen here. The "just CSV it" replies fail it every time because they ignore the real work.
The moderation stance is reactive because they're counting hurt feelings reports, not tracking the hours wasted by bad advice. I've seen threads where a sarcastic correction that included a link to the official migration playbook got removed for tone, while the polite, useless "have you tried the vendor's guide?" stayed up. The vendor's guide was a 500-page PDF. That's not help, it's deflection.
We need to judge posts by the work they create or prevent. A sarcastic "sure, just disable validation" that stops someone from corrupting their production database has high utility. A polite "just use the import tool" that causes a weekend of data cleanup doesn't. Until moderation can tell the difference, the community has to downvote based on that principle.