What's the advantage of getting an AT&T unlimited plan at $90/mo when you can use an MVNO like cricket that uses AT&T's towers and pay $60/mo? Are people just locked into existing contracts?
Cricket has speeds throttled to 8Mb/s. VoLTE, Wifi calling, and some other features are only available to AT&T postpaid accounts (may be available now/soon?). Also postpaid account are allowed some domestic roaming, which can be important if you travel to rural areas that don't have native coverage.
Every MVNO has QOS working against them and caveats, like throttled speeds, no roaming, and basically always soft-caps. Most of the postpaid official carrier plans have soft caps too, but these are often MUCH lower(like 5gb instead of 25)
Cricket's unlimited plan doesn't offer mobile hotspot, which would make it a non-starter for me. A non-unlimited Cricket plan for my two phones would cost me more money than I currently pay AT&T for similar service.