Why is the rust-toolchain file using 2022-11 nightly?

[weezy20]

To me this https://github.com/paritytech/frontier/blame/master/rust-toolchain.toml seems to be unnecessary.. Any particular reason why we are using such an old nightly? The recent versions of substrate (polkadot-v0.9.40 and above) compile and run fine with latest stable rust.