This is true for most genetic engineering applications but not all. Somatic gene therapy has been successfully performed in a few cases. There will almost certainly be more applications in the future, and it’s reasonable to expect that they will be able to handle some prevalent diseases (such as all types of diabetes).

The only approved genetic therapies (Luxturna, Strimvelis, Glybera, others) are all for children or adults. To say you can only use it for germ line modification is just plain wrong.

True but that’s purely for legal/ethical reasons, not (directly) scientific ones. Most scientific uses of CRISPR (and other gene editing techniques) by far happen in the germ line. Germ line research (and, thus, applications) are lacking in humans not because it would be scientifically hard, nor because it won’t eventually happen, but because of hard ethical problems with such research.

And the comment that I replied to implies that it is talking about certain applications of genetic engineering which have to happen in the germ line. So I disagree that what it says is “plain wrong”, it’s just incomplete.

I’d say it’s less for ethical reasons (though that’s true) and more because the technology for modifying germ lines is nowhere near as advanced as inserting DNA into non-germ line cells.

We have no idea what the impact would be for modifying germ line cells in a developing human being.