It depends on what you consider a "pharma company". If the major companies acquire drugs, then it could still be argued (and I'm sure people do) that the drug prices, being dependent on patent rights, are indirectly paying for R&D. Just because it's not the same company doesn't mean that the ecosystem doesn't depend on the patent rights to finance the research.
I'm not completely confident of the necessity of patent rights as they are, but it seems logical enough on the surface. I can't assume that entities which engage in transactions together are independent.
It also doesn't mean the ecosystem is dependent, either. Disney made lots of money selling movies based on stories in the public domain. Just because a middleman exists doesn't mean the middleman is paying the ultimate source in proportion to the money the middleman takes.
> [Frederick] Banting felt “…that as a physician who had taken the Hippocratic oath he could not be party to any patenting of a discovery. ... John J R Macleod, with whom Banting shared the 1923 Nobel Prize in Physiology or Medicine, similarly declined to be named on the insulin patent. However, neither [Charles] Best, a medical student who had yet to swear the oath to Hippocrates, nor [James] Collip, a PhD biochemist, faced any ethical dilemma and were named as inventors, although for $1, Collip and Best transferred all rights, title, and interest to the Governors of the University of Toronto. Banting, Best, Collip, and MacLeod all believed that insulin should be made as widely available as possible, without any barriers such as cost....
I think the proper conclusion is "no information" - the fact that redistributors are being paid what they're paid does not tell us anything positively or negatively about the necessity of them being paid what they're paid. You'd need to look at their actual costs, and more importantly the market of those costs: if they stopped paying researchers, what would the market effect be? (Perhaps they could fund research grants instead of discoveries, incentivizing everyone to work on the problems most interesting to them regardless of profitability, and thereby increasing research into cures for rare diseases.)
I'm not completely confident of the necessity of patent rights as they are, but it seems logical enough on the surface. I can't assume that entities which engage in transactions together are independent.