Mainly when you are building a single-purpose , “appliance” device and you have the bare minimum of RAM/storage available. You just want to get the board powered up and initialised and then jump to your application.
So you build a kernel with only the correct drivers you need, you skip initrd, you skip initscripts and (lord forbid) systemd, you just jump straight to your program, with possibly busybox available if you need debugging.
Edit: I’m talking more about building it from scratch here, not LFS. Regarding security issues, you then “only” have to deal with kernel exploits, with a limited surface as you have limited modules linked, and exploits in your application.
Then you’d escape them by using another character in front. But if their data format is ASCII text or is guaranteed not to have characters below ASCII 32 then using ASCII delimiters is fine.