There is nothing fundamentally wrong with editing germlines.

The reason this method of genetic editing affects the germline is that it affects the whole body — which therefore includes the germline. It can be done early in development.

To cure genetic problems that result from genetically-guided incorrect fetal development can only be done in this way. Once you're going to do something so fundamental, there is no benefit in leaving the problem uncorrected in the germline, to spring up again in the next generation, even if that could be done.

There is nothing fundamentally wrong with the approach, but in the present state of inexperience, there are risks that things will go wrong. But I suspect that many of them could be avoided by aborting fetuses that are developing visibly wrong.