In the observation I (tried to) link which prompted this suggestion there were two users who both marked it inaccurate, I marked it accurate and that wasn’t enough to remove the Location is inaccurate flag. So even if the observer did flag it Accurate themselves nothing would have changed. That’s actually exactly what happened in this example, if bouteloua had not seen my comment and come back to remove her vote the observation would still be considered innaccurate.
It’s not that common, but on occasion I’ve seen observations with a lot of people all flagging the same issue. Albeit usually with a zoo animal marked as Not wild.