Channel factories only work as long as all participants of the factory want their Bitcoin inside the LN. As soon as any party wants their Bitcoin in their Bitcoin wallet, the factory needs to close all channels. This makes is unusable in the real world as people can and will not commit their whole networth into static channels that need settlement of 100 or so unknown parties until they can send it anywhere else.

All of this also completely ignores the LN routing problem which is conveniently left out of the LN whitepaper as it is actually unsolvable at large scale unless you have very few supernodes coordinating everything. In the real world those are commonly known as "banks".

You can splice out bitcoin from a channel without closing the channel. The channel balance can go almost all outwards (some is kept to be able to pay transaction fees). In the channel factory scenario, one participant can receive bitcoin on chain without closing the whole factory. However, they will have to pay the transaction fee which could be prohibitively expensive.