Was that the fault of the broadband provider or was that the fault of the indoor WiFi? Is it possible the router has so much interference from all of the neighbors and everyones using 2.4 GHz? What if that example had a cable connection with 960/40 mbps and they're limited to 5 mbps up because of the in house WiFi solution?

Would upping the broadband plan to 1000/1000 fix that problem?

Over a few decades of customer support using screen sharing and also testing new software releases I have come to understand that asymmetric speeds are not satisfactory. I assume that is why ISP marketing and speed tests emphasize download speed with no other applications in use, minimize upload speed, and generally ignore performance under load (see buffer bloat).

This is not confined to just one end of a connection. Clients using a VoIP service encounter terrible voice connections while screen sharing or receiving software updates. Any software updating from the support end using the typical (comparatively minuscule) upload speeds are expensive, not for ISP charges, but for the time required. For these applications (which do not include family sharing) having only 100/100 is immensely more productive than 100/10. Of course, 1000/1000 would be delightful if ‘affordable’ to a single entrepreneur.