That's to say, the option [Goal: Duty Completion] should not be available until after you've run at least one of the two practice options, or some other alternate to prevent people from signing up to Duty Completion when they have no prior experience with Savage fights.

I've ran Susanoo a few times now through Raid Finder, and every single time there was someone first-timing the fight (noticeable because they skipped no cutscene and failed most mechanics).

Raid Finder is the premier tool for players who want to just queue and do the content with randoms, but its value is being under-mined by these selfish players who loath self-improvement and choose to be burdens on the parties unfortunate enough to be matched with them.

At the very least, demand they have experienced the fight once before they try to shoot for Duty Completion.