Stellar experts, please explain Liquidity Rating

Okay, so from StellarExpert API – Asset Rating, they say the following:

“market liquidity (based on the relative slippage of {ASSET}/XLM market)”

And on Aqua.network, they say:

“The core use case of Aquarius is to increase liquidity on Stellar. We plan to achieve this by incentivizing SDEX market makers & AMM liquidity providers.”

Am I correct in assuming they're incentivizing SDEX market makers because both the AMM liquidity and market making (placing limit orders on the SDEX order book) help reduce slippage and improve the Liquidity Rating?

Stellar experts, please explain Liquidity Rating