In some sense all TDR is marketing. It allows DeFi apps to have higher APR that attracts more customers.
TDR are also a way to distribute ALGO to users which is what the zealy campaign does. In my opinion the zealy campaign is very well crafted. I have been participating for several rounds and if you want to be rewarded you need to have an important on chain activity related to Folks Finance and to produce meaningful quality content. Of course you’ll have some bots trying to participate but they cannot win rewards.