I have not heard this about "most shops", in fact I have never worked in an org with a functioning software R&D team (unless you count enterprise architects choosing vendors).

No but I've seen similar dynamics play out at most companies. Broadly, "product teams" focus on customer feedback and delivering value to customers, at the expense of technical debt and lots of fickle requests. "Infrastructure" teams are heavily insulated from customers and deal with a more long-term roadmap and fewer changing requirements.