It's not meant to be a democratic poll, but rather a PR stunt.

They did this kind of a poll in 2012 after they fucked their game up with Evolution of Combat update and most people quit as a result, but then they decided to make a vote if they wanted old school servers back which blew up on all the corners of the internet and it was the most talked about thing.

This poll works in almost exactly the same way and their goal is for RS3 to gain new players. They know 100k votes will be easily met given how there's around the same amount of RS3 players and OSRS players will act as "cavalry" that'll come into aid due to social media's call to actions, they're just hoping it'd create enough buzz for people to pick up that version of the game again or people to learn about the game through media. The poll had no chance to fail.

If you don't care enough about the game to participate in the vote, why the hell should your voice be taken into account anyway?