Oh please, there's no in story evidence for any of this, it's all wild conjectures to try and rationalize away a choice that's pretty much entirely based in sentimentality. Most of the post is just pretty sounding ideas that don't have any in reality, we don't need to make our family strong/useful for them to matter. Even if we wanted we couldn't do it regardless, our mom is a middle aged lady that'll never amount to much cultivation wise and us spending more time with her while we're at the sect won't change that, Biyu is too young to start cultivating, even if she does have potential (which we don't actually know for sure) she won't be doing anything cultivation wise for a long time still. They can't carry us and them being weak is perfectly ok, especially since we can't actually do anything about it.
The people claiming it'll be good for our domain just want to have their cake and eat it too, family is tangentially related to home and there's no real proof that doing this will help it beyond speculation. Stop trying to claim that this is both the best choice for our cultivation and the "feels good".