The non-synthesizable features of Verilog not only work in current simulators, they were expressly developed for that purpose. Verilog has those features to describe conditions that might exist in a semiconductor as manufactured, but aren't part of any design, so that they can be more accurately simulated. For example, a pin state can be unknown, or two pins can be connected with a delay line. These allow a real-life semiconductor to be characterized well enough to insert into a simulation of the electronics circuit as a whole.

It's more akin to directives than instructions. Debug instructions can also serve a similar purpose, although they actually run on the hardware, whereas compiler directives and non-synthesizable verilog instructions are never executed.