That...………. is not entirely correct.Smokeless shoot amazingly well. If you want to use one in place of a rifle in the general season, they are the way to go. But, if you want to use them in the mzl season, very few states that the are legal. I contemplated this a year ago.
Just because a rifle may be smokeless rated, does not mean that it won't shoot black powder or any black powder substitute. And they are more accurate using BP or BPS than mass produced production rifles.
Now granted, in some states that remain with archaic laws, they may not be able to be used even with BP because they may be have caliber restrictions, or a bolt action, or in other words, not a side hammer. However, there are actually very few states where a custom rifle, using BP or BPS would not legal during dedicated muzzleloader seasons.
Read and follow your rifle's owners manual. Always.