Even if that were true, it still wouldn’t be an excuse for spamming the network, but rather evidence that one needs to get a node firmware that honors TTN rules.
But for the most part, it is not true, because with a few exceptions (whose manufacturers may need some pushback) most TTN nodes with certified stacks don’t have a unitary firmware that reads sensors and transmit, but rather have a module running a certified stack, and an application firmware in a different chip requesting it to send things.
In such case, it’s the responsibility of the application firmware to ask the stack what spreading factor is being used, and back off the transmission rate accordingly.
Getting misbehaving nodes into the field is really, really intolerable - because once they are out there, for the most part, they won’t get fixed.
Johan and Wienke explicitly stated a device is allowed to exceed this one day if it backs off the next day.
This just circles back to the basic fact that to have any confidence that the transgression will be time-limited, backoff must be autonomous behavior - it cannot be downlink commanded behavior, because the delivery of downlinks cannot be guaranteed.
Consider what happens with a bunch of nodes that will only back off in response to a command: once they start stepping on each other’s transmissions, you can’t command them to back off - the situation is unstable because congestive failure causes positive feedback resulting in more failures. In contrast, a stable system does its backoff autonomously, and only ramps up in response to encouragement from the network (specifically in the form of a ADR sending it to a faster SF).
And it’s not just a politeness issue - frequently transmitting at slow SF’s is a battery killer, too. The last thing you want is a node that’s battery expenditure increases when it’s out of touch of any functioning gateway.
This policy is not instituted to ban nodes from the network, just to make sure no one device monopolizes the shared resources.
Exactly - for the community network to work, users need to take responsibility to deploy only well behaved nodes which autonomously reduce their transmit rate when not receiving downlinks.
What we really, really, can’t have are irresponsibly broken nodes that increase their airtime utilization when they aren’t getting a response from the network.
Just because that’s what was bought off the shelf is no excuse - doubly so because in most cases it can be fixed in the accompanying custom portion that injects payloads to send.