I think he may be right to an extent, and it could probably be fast if there are enough small cells.
In Canada, I think there are still lot of neighbourhoods that don’t have FTTH (including mine). In my case our options for getting internet are cable (which tops out around 1.5gbps down but only like 50mbps up), or telephone (max offered is about 50mbps down).
Both providers are building out fiber slowly and have been for years, but I’d imagine if the small cells themselves aren’t too expensive, it could be a lot cheaper for them to just run the fiber along the street and put small cells as needed (without having to rewire every house).
It won’t be as good as fiber, but I could see it being better than phone lines especially, and good enough for most.
It might also make it easier for other providers to enter a given market (currently we only have 2 choices, some places only have 1) which could be good for competition.
How much signal strength does the mifi say it’s getting? Can you move it up to a higher floor or try it in different spots (near windows) to see if you can get a better cell signal?
Calling it a MiFi suggests to me it was meant to be portable. If you’re using it for permanent home internet, perhaps Verizon have something bigger that would perform better (bigger antennas, 5G, better CPU, etc)
With any wireless tech, you’re sharing bandwidth with others around you on the same provider, so it’s more likely that you will run into capacity issues vs if you were to spend the $5k for the wired install.