A musket is also battle-tested, but it was replaced because it is slow, hard to operate, heavy, and in the end if you tried to continue using one, you lost.
M4 is similar. It's just a macro processor. If you try to make it work on a problem that requires more, it will backfire in uncomfortable ways.
Ah, the joy of cherry-picked analogies. Let's replace the musket with an AK-47, how does it look now?
Yes, M4 is a macro processor. A pretty decent one that is well-known and will not surprise you with incompatible changes or newly introduced bugs. Nobody suggested using it for more.
AK-47 had been superseded by AKM after less than 10 years in service. AKM was, in turn, superseded by AK-74. And AK-74 has been superseded by AK-12. The last transition, in particular, was heavily motivated by ergonomics and difficulty of adapting the original to typical modern circumstances of use.
So, I'd say the analogy still holds up pretty well.
I'd rather have someone learn to use M4 when needed than have "some Python" replace M4 in an important project. But that's just me, other people like building sand castles.
M4 is similar. It's just a macro processor. If you try to make it work on a problem that requires more, it will backfire in uncomfortable ways.