Just to put it in a verrrrrry general setting:
Not being able to move symmetrical (and develop both sets of large muscles evenly) will cause spine deformities fast - so why do you want your still growing babies deformed?
That is not only cruel, but also bad business -> do you want to be known as the person who deliberately causes deformations in birds and sells them broken?
Any clip that causes bird to break or fracture a keel/bones/beak is way too severe -- it is simple physics.
Also a no-brainer I would think (and also animal cruelty: to restrict an animal in such a way it causes self-harm).
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Cliiping birds wings while still verry young is already proven to be a bad move - it stunts their development (physical and psycological).
They can be just as easily tamed while fully flighted - there is plenty of information out there how to do so; this is no longer "a trade secret" or something "only for professionals".
So it is complete unnecessery and detrimental to their health (short term and long term)