Correct but remember some platform can now support "e-SIM".
Cost is one big concern about WiFi. Particularly when one needs a cable plant and a switch.
Next biggest problem with WiFi? Everyone's favorite: Co-Channel Interference.
Finally, the last biggest problem with WiFi? Roaming
Let's face it. 802.11 WLAN is a shared spectrum. Every-man-and-his-proverbial uses these channels and everybody plays by their own rules. LTE is different. Mobile phone providers buy the spectrum. And they do not come cheap either. The spectrum that each provider bought is theirs. They can do whatever they want with the frequencies. They can splice them. They can dice them. They can put cherries on top. They bought the frequencies, they can do whatever they want. Anyone caught using a provider's frequency without their explicit permission will be in trouble and it will be in the millions of dollars in penalty.
With LTE, the provider(s) will provide a DAS indoors. Those DAS use a low-powered amplifier. Because it is an LTE frequency, it is a guaranteed spectrum. There is no co-channel interference from anyone device that is broadcasting. LTE is a guaranteed spectrum.
End devices in WiFi are responsible for "roaming decisions" and most often these devices do not follow the agreed (roaming) rules. In LTE, the provider will calibrate the DAS and will make the decision which devices each antenna can allow and which clients to "push" to the next antenna. The carrier can say to the device, "Hey, you. Why are you still hanging around this antenna. Shoo! Get off this one and go to that one over there!"
As a bonus feature, there is another thing an LTE network can do that a WiFi cannot do: COVERAGE. Walk out of the office with an LTE device and the device will roam outdoors into the open. Unless someone plants a WiFi AP outdoors, it is not happening in WiFi.
