The biggest points against it being anywhere near as easy as "teaching an adult a language" are: the existence of masking, and the limited success of behavioral interventions - especially in adults.
If people find it easier to learn and apply the workarounds than to learn the thing itself, then, clearly, something prevents them from just learning the thing itself. Behavioral interventions being generally more successful the earlier you do them lines up with that too.
Maybe there are "low hanging fruits", simple interventions that work well that we are yet to discover. But it's not like no one went looking. And the fact that we are yet to find them weights against it.
If people find it easier to learn and apply the workarounds than to learn the thing itself, then, clearly, something prevents them from just learning the thing itself. Behavioral interventions being generally more successful the earlier you do them lines up with that too.
Maybe there are "low hanging fruits", simple interventions that work well that we are yet to discover. But it's not like no one went looking. And the fact that we are yet to find them weights against it.