Comment by VLM

I pulled several thousand lines as a kid starting out in Gen-X era and you are completely correct with one scalability and labor cost issue:

Real cat5 and ethernet connectors just work and phone cable and phone plugs just work, but if you mix them you'll get all manner of expensive labor costs trying to figure out jury rigged solutions.

At one client they used two pair for business phone system, we're on a cable pulling team and one guy punches down the blue and green pairs the other side punches down blue and orange pairs (essentially a 568A vs 568B violation) and we spend SOME EXPENSIVE TIME trying to figure out why the cable toner "proves" we are on the same cable so it can't be a wiring fault.

Or the stereotype of the halfway colorblind guy at the far end working in the ceiling, on a ladder, in the dark, swaps the orange and brown pairs as happens sometimes.

Oh even funnier is there's always "that guy" who is too lazy to pull an additional cable to a new phone, so he steals some pairs from a nearby phone, somehow knocking out both phones in the process. Such a headache.

Labor for troubleshooting miswired cables/jacks is SO expensive its just cheaper at work to install phone lines using phone line parts and ethernet using ethernet parts.

The arrival of VOIP phones around Y2K, somewhat after my time, must make life so much easier. And now nobody uses wired phones everyone has a smartphone.

At home if you're doing one line and its a hobby so your time is free, then your strategy does work.