These days, people want to make money off everything. Just as you said giving merits and earning merits are good. It helps build confidence in the Merit receiver and promotes trust among users. Merits are supposed to be earned for quality posts, but on this platform you see many quality posts without merits. A lot of discussions on here are so valuable, priceless and applicable if the readers put them to use. But a situation where merits are not giving to those who deserve them, on the mere excuse that there are a lot of spam discussions or probably because the merit givers don't know you personally. All these makes it more bias and Trading of Merits for money is in no way making it better.