The winner of the polls is the one who brings more friends to vote for them, rather than the one who made the best entry?

Yes. The winner of the poll is the one who brings more of their friends, their audience to vote.
And thats the least we can do for musicians to entice them to build an audience. Ofc, that wont win them the weekly prize on its own but it will help them win and help with their music getting out to people.

I am the best singer in the world, none of the greats come even close... Freddy Mercury, Beyonce, Siniša Vuco... when I'm alone in the shower.
No one else there though... Music should be played for an audience. Not just for 2 judges.