1. I think if someone is gonna earn money from this site then its natural that the site can ask them to pay for helping them earn.
2. All those who post YouTube videos can't be asked since they never get many views to pay. But certainly those who have a lot of subscribers and get lot of views from IRI too, can be asked.
3. But since Moderator doesn't ask, then those who earn from the videos can come forward and help on their own. Whatever they wish.
4....
more... It all depends on individuals. Some may say I never earned due to IRI, all on my own and may not be willing to pay up. We have seen in so many interviews that many IRI members don't even acknowledge the existence of IRI, similarly YouTubers may deny that IRI ever helped them with the subscriber base and views. So it should be voluntary.