The main barrier to replicating an amplifier by a computer was in realtime processing of all those components without lag. When processing power got good enough it was then up to sound engineers to program systems to deep fake the real deal.
Digital aliasing is still a problem to varying degrees with every commercially available modeler/profiler.
The processing hardware required to do an optimum job is simply not cost effective for any production unit.
Doesn't matter how good the sound engineer/programmer if he's working with limitations in processing
due to costs.