Are there some things that just can't be emulated with VSTs?
Age old digital vs. analog debate I guess.
With whatever limited technical knowledge I hold, I would answer that question with:
theoretically? no.
practically? kinda.
You speak of pedals, what they offer that is most obvious is hands on / direct and real time effectiveness. Also dedication, and in a way that's very crucial. Sure you can install 3000 plug-ins in your DAW or sequencer, each with 1000 parameters, but before you get even one of them to do what you want it to do and really get to know it through and through, well in many situations if you had acquired the exact pedal you need to get it to do what it is exactly you need for it to do... it would have been more convenient, immediately rewarding and gratifying, etc.
But technically, you can get VSTs and plug ins and patches to do potentially just about anything. So it becomes more a question of what you're comfortable with, what your wallet can afford, and most importantly what is it you're trying to do?
Because for very many things, pedals (or any hardware really) can be much more convenient, offer a quality which is easily testable / quantifiable, reliability, ease, gratification, etc. which software CAN achieve as well, don't get me wrong, but it's just another ordeal...
That said, I believe that digital avenues offer potentials yet barely explored.
It's the end user that really defines where the creation goes, not the tools, y'know?