Are folks who say this not using containers? R has been at least as easy to dockerize as Python since whenever Rocker started, only easier with more recent package management options. Once dockerized, my only R complaints are around logging inconsistencies.
I used to think the culture around R meant that productionizing arbitrary code was harder on average than in Python...but years of suffering with the pandas API has me thinking the opposite these days.
I can trust a junior R dev to write reusable pure functions but can't trust a senior Python dev to do the same!