> protein folding (reduction to quantum chemistry),

I am not sure in what sense folding simulations are reducable to quantum chemistry. There are interesting 'hybrid' approaches where some (limited) quantum calculations are done for a small part of the structure - usually the active site I suppose - and the rest is done using more standard molecular mechanics/molecular dynamics approaches.

Perhaps things have progressed a lot since I worked in protein bioinformatics. As far as I know, even extremely short simulations at the quantum level were not possible for systems with more than a few atoms.

That's a practical limitation. There's no barrier in principle to a complete reduction.

I meant that the word "reductionist" is usually an accusation of ignorance. It's not something people doing reductionist work actually use.

But that common use of the word is ignorant nonsense. So, yes, someone is wrong on the internet. So what?

The context here was a claim that reducibility is usually a goal of intellectual pursuits. Which is empirically false, as there are many academic fields with a negative view of reductionism.