As OTAA needs a downlink, and downlinks are very expensive (as gateways cannot listen while transmitting, and gateways need to adhere to things like duty cycles as well) and fragile (the device might not receive it), this simply does not apply to LoRaWAN. Also, a join would probably use more battery power than using some sleep to preserve state in memory?
Some modules simply don’t need a lot of power to preserve state in memory. Like: