Shared libraries/dynamically-linked libraries, along with faster storage solve a lot of the historical optimization issues. Modern compilers and OSes general take care of that, if the right flags are used. With very few AAA games using in-house engines, it's even less work for the studio, supposing the game engine developers are doing their jobs.

That said, you do still have a bit of a point. Proper QA requires running the software on all supported platforms, so, there is a need for additional hardware, if not offloading QA to customers via "Early Access". Adding to that, there are new CPU architectures in the wild (or soon to be) that weren't there 5 years ago and may not yet be well-supported with the toolchains.

Gaben is absolutely correct on practice though, it's a distribution problem. EA, Epic, and the rest trying to force their storefront launchers and invasive DRM that makes the experience worse for the end users drives people to pirate more.