There are some very interesting things you can do with some DeFi code, things that nobody is doing.

Most DeFi code is open source. That means you or I can take it, change it a little, leverage the work of others (which is half the point of FOSS) and make cool things.

The DAI contract code and MakerDAO code is really cool, and can be used to create a collateralized asset pegged to anything. You can peg to any currency you want, you can peg to any asset you want just by changing the Oracle a little. You can peg to gold, table salt, anything you can get a reliable price feed for. You can also peg to things that were impossible before this. You can peg to CPI, the S&P500, you can create your own index. The code is there. All it takes is a little foresight and understanding, a small amount of work, and anyone in the world can create synthetic assets pegged to any real world measure of anything.

You can do a lot more with liquidity pools than just replace order books, although that's cool in and the most revolutionary use of them. You can do what Bancor did and create basket funds with them.

You can, right now, clone the uniswap v3 code and publish it to a contract, in violation of the license, and nobody can stop you.