I think a lot of you are failing to connect the dots.
Once all of the guns require a serial number and all transfers have to be papered, it becomes much easier for them to go out and get these firearms (or arrest and ruin those “dangerous criminals” who no longer have them) when they determine that these “implements of war” are no longer legal, because only the government is qualified to wage war.
Additionally, for those in the “who cares because I don’t own any personally made firearms” crowd, I sure hope you also don’t change triggers, barrels, modify bolts, add muzzle brakes, etc, because all of those things are about to become illegal too, unless you have a “manufacturer“ do them. Don’t believe me, check out the proposed definitions of “firearms“ in the new ATF interpretation,specifically the language related to “fire control parts and housings”.
This is just the next step towards what they really want which is all out bans/steep restrictions on ownership. If you don’t believe this then you have your head too far up your own arse to have a serious conversation with. Sorry.