In the Netherlands, a petition was required to force a national referendum. Online or offline doesn't matter. You needed to reach some percentage of the Dutch population in signatures, I'm not sure about the exact number, but they did and we had a referendum on mass surveillance and people voted against.

That's when the government decided these things are kind of a nuisance and abolished the whole concept of referenda, even advisory as they were

I love the ruling party

But anyway petitions aren't necessarily useless, also for media attention on a topic if it goes well