The article makes a great point early on: hearing voices over VOIP is markedly different than over analog phone lines. The robotic voice and the weird compression when your connection isn't good are common for me. Worst of all is the 0.5-1 second delay I still sometimes hear, on local calls no less! If the same call was being had over a phone line and we were in the same country, the audio fidelity would be excellent…
That's funny - my experience is digital is much clearer than an old analog line.
Analog Land Line local call > WiFi Calling through cellphone > Analog long distance call > 3G/4G/5G Cell > Home VOIP service > Zoom/Meet/etc.
With the first two pretty close to identically high quality.