Blind to one's purposes?

A typically ignorant comment on purposive behaviors in organisms, recently received (at another site) went like this: "Likewise, there is no purpose in a human sense behind a stick insect's camouflage. It just so happened that its ancestors did not die because they just happened to have random mutations that conferred this morphology when without it they would have."
Except that commenters like this fail to realize that the individual entity here will be born with instinctive knowledge, in the form of an inherent strategy, so that if this insect responds in a certain way to threats, for example, the morphed structure is expected to be useful.  The insect doesn't have to know the purpose to act exactly as if it did.  Somewhere back down its evolutionary line, something, in some sense, was cognizant of the deceptive value of the camouflage, whether or not that something was instrumental in its morphological acquisition.
Camouflage has become that morphology's acquired purpose, because the insect uses it deliberately to achieve that purpose.
It's simplistic to explain that "without it" the insect would have died, yet "with it" was allowed to survive, regardless of any advantage the insect would have learned to take from its acquisition.   Of course these simple folk might not accept that an insect could learn, or worse, that such learning could be heritable.  The watchmaker, if blind, can't learn by his experience to see the watch - or can he?

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Deceptive strategies being common (if not basic) in the biological world, it's more likely that the opportunity afforded for the adaption of the archetypical mimicking strategy drove the evolution of the structure, rather than the structure having influenced the development of the strategy.  One reason being that strategies adapt themselves to environments, and the forms that activate their functions are made to suit their strategic purposes, rather than the reverse.

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But wouldn't this mean that life forms engineer their own structures?  If so, how would they manage the replication process?  Wouldn't it  be the same way they supposedly manage to replicate a mutation "engineered" through (somehow) selecting from a series of random trials made by some unknown force of nature?
But then what exactly is the makeup of any such replicative mechanism?  If it allegedly allows the organism to copy an accidental restructuring of a gene, why can't it copy one that has to  some extent been deliberately restructured?  Either way, it will have taken advantage of the randomness of opportunity. So the question would seem to come down to this:  Can an organism participate at all in its reconstruction?  Because it surely seems that all those we've been able to examine want to.

(Disclaimer: The preceding questions have been for the most part rhetorical.)