On my system, egrep and fgrep are _already_ shell scripts, just changed to add the stupid warning:

    $ cat =egrep =fgrep
    #!/bin/sh
    cmd=${0##*/}
    echo "$cmd: warning: $cmd is obsolescent; using grep -E" >&2
    exec grep -E "$@"
    #!/bin/sh
    cmd=${0##*/}
    echo "$cmd: warning: $cmd is obsolescent; using grep -F" >&2
    exec grep -F "$@"

Looking at src/egrep.sh in the git repo[1], I see that before this warning was added in 2021, the last change was back in 2015. In fact, since the git repo history began in 1998, there have been a total of 4 changes to this file. Clearly the maintenance burden of these scripts is not sufficient to require the maintainers to drop them. My guess... this is being done out of some weird sense of purity over practicality. Bad call by Paul Eggert IMO[2].

1: https://savannah.gnu.org/git/?group=grep

2: commit a9515624709865d480e3142fd959bccd1c9372d1 added the warnings