Staking aave is similar to staking chainlink community pool (not using SDL). You can withdraw with cool-downs and token easily goes back “into circulation”. There is no other market created.
In locking aero or sdl, you create an NFT that is tradable from the underlying asset. These new veTokens now have their own markets. As the secondary market grows, you will now have a fictitious representation of SDL value as we’d be double counting the reSDL NFT market. I can’t think of a scenario where that is common practice.