A scheme, where we together put small funds, we get more rewards, while we add more, the reward ratio decreases, feels kinda spam. Isn't it?

Locked staking mechanisms do so. The worst part is most get lured to incentives percentage before fully realising the assets are locked and can't get any price surge gains in between.

I prefer where I can exit any time I want. Leveraging both the staking yields though it may not be that high and the opportunity to cash out any price gains. $RDAC provides both, $USUAL used to, but has recently added lock mechanism.