Without liquidity it is impossible to survive.
There are a lot of DeFi projects and there is a big competition among them.
In such a competition win only the best projects with biggest liquidity and big choice of different tools.
Due to the stricter regulation of cryptocurrencies and various introduced restrictions, many users are afraid to store their money on centralized exchanges, preferring safer decentralized platforms.
Very often accounts of users on centralize exchanges are blocked for different reasons but it is imposible to block the account on DeFi exchange.
That is why DEX so popular now and in demand.