Every one do as they do. Adult people in question. But it is vain to claim that you get from emergency cells as good as from grafted.
Now we talk only about queen's ability to lay. But rearing queens is something else than that.
You may rear one queen from your hive, but do not advertise that it is as good as selected and grafted. To select a mother hive from 10 hives than from 200 hives.
And the rearing queens is so expencive operation, that queens are not free at all
If you rear one queen, quality will be poor and price is huge when you calculate as a loss of honey yield.
Best way is buy a laying quality queen, and make a nuc. That is scientific.