VSTs are actually only simulating FM-synthesis, and approximating it with wave tables.
If you go back to Chowning’s original paper & subsequent patent on FM synthesis, it has always been a digital algorithm. There’s no simulating FM in VSTs, they generally implement exactly the same algorithm used in the Yamaha DX7. The whole reason for FM was that it was a simple, efficient synthesis with almost limitless timbral possibilities.
If you use analog FM synthesis, or the simulation in Rack, it’s bit different. Partly because it isn’t implemented as a table lookup as Chowning’s algorithm does.