[DropInIn]

I'll put forth that nothing of this sort, from the semiconductor age onwards, can be an artifact as we have far more readily available and detailed records to work from.

Such graffiti is only an artifact when it's purpose, history and other aspects are lost to time due to lack of alternative documentation.

In effectively all cases these days there is simply no additional value obtained from graffiti like this, unlike that of street artists doing murals or painting trains.