I've been a member of Yoors for a year now and I love writing and reading here. Whether Yoors is timely in payment or not doesn't really bother me. I like it's a nice little extra income.
I have been at Yoors for 2 years, and although the payment is an encouragement of this website and it is appreciated, we never know exactly when it will be done, I think this has disappointed a few, there are very good colleagues who are no longer there, and I know that they are on other pages
I personally believe that payment is not mandatory, both Henkjan and the Yoor's team, it does so as a way of rewarding those who manage to make good publications, it's like a kind of reinforcement for your good “sharing” and it's something to be grateful for and always support this project, as you yourself say.