Downlinks are very useful: for OTAA, for ADR, for remote configuration, maybe even for a remote reboot to allow for joining a different network. (Unfortunately, downlinks for confirmed uplinks apparently have a design or implementation flaw.) Downlinks should work properly, and if not then one should fix that. But controlling things is just not a good use case for Class A LoRaWAN.
Just for the sake of completeness, though already mentioned in many other places: even if downlinks work fine, there’s also the limit of 10 downlinks per day. I’d assume that retries for confirmed downlinks count against the Fair Access Policy as well, as the network cannot be blamed for that.