The larger thrust of my essay is that simple feature checklist marketing and product specification fails to consider a larger ecosystem and workflow of usage. The fact that much of the intelligence of the system was "women's work" (e.g., provided by secretarial and switchboard staff), made it all the more invisible.
Regarding the limitations of the post-1980s "smart phone" ecosystem (both desk and mobile devices), the limitations and UI/UX failures:
1. Apply to a number of different devices. Not merely flagship smartphones, but several other variations on featureful telephony equipment, including a number of generations of office phone systems (typically Rolm desksets), VOIP systems, and consumer landline / wireless handsets, etc., with which I've had direct experience. These tend to exhibit a range of UI/UX failures, to a greater or lesser extent.
2. The opening quote was from an aquaintance, who's more than slightly technologically literate.
3. The statement isn't absolute, but conditional. Frequently implies "not always".
Comments so far seem to miss both the focus on overall workflow, and the nuance on feature completeness and/or suitability.
Perhaps I'm a less effective communicator than I'd hoped.
Perhaps the technological blinders are more formidable than I'd feared.