There is no point in rating the story down, even genuinely bad one.
On Scribble Hub, ratings are rare and far between. Clicking away, ignoring and not following it is entirely sufficient in keeping it out of the Trending. No one filters them by rating either. It's just being mean, for no reason, not helping anyone to find the better stories. Filters are simply not reliable, and it is better to check by genre. Good stories may even lack rating completely since there is fewer reviewers going around.
On Royal Road, one bad rating would forever destroy the story's chance to receive any other feedback, or readers, since the system is far more competitive, and far more unforgiving. They can't be removed, even after issue that caused the low rating is fixed, but can destroy everything in the instant preventing it ever be corrected. It also creates a constant infighting where downvotes spread the misery around by downvoting others, eventually reaching the story you like too.
My personal policy on SH is to rate 5 if I really like it, and do nothing if I don't.
On Royal Road, I five star everything, even stories I hate. I used to rate more realistically, but then I learned how toxic the RR system can be, so all five. Only stories that have rating lower than 5 are those who I reviewed long time ago in the past and damage is already done. No new story should receive low rating from me there.