It's not about possession, but intent. There aren't any good reasons I can think up as to why a person would need to carry an assault rifle around in plain view of the public. A handgun is far more reasonable, and also a different discussion.
You won't find me defending the 'open carry' idiots who go walking into Panera or Target with a rifle slung over their backs. That kind of intentional provocation is a breach of the peace. But my question was why ban possession/ownership and
legal use (target shooting, varmint/pest control, home defense), and you say it's not about possession. It's a ban that criminalizes possession of property that was previously perfectly legal, so I don't understand your response. Sorry if I missed something in an earlier exchange.
Anyway it's New Zealand, so it's New Zealanders' business. I don't know the context or history of civilian firearm ownership in that country, or what protections their Constitution may guarantee against rule by executive fiat. Seems like none.
Guns are not being banned, but high powered guns are.
Just for the sake of truthful information being available here - an AR-15 rifle in its standard 5.56mm caliber is not a high-powered gun. It is effective for military use because the small, light and high-speed projectile it shoots tends to tumble and fragment on impact, resulting in wounds that are more certain to incapacitate. That means for every person who gets shot, more personnel must take themselves from the fight to assist in transporting the wounded.
Compared to the 30.06 rifles used by the Americans in WWII, the 7.62x51 caliber they went to in the 50's before transitioning to the M16, the 7mm rifles used by the Germans, the .303 Enfields used by the Brits, the 7.62x54 Mosins used by the Russians, and any rifle currently and commonly used to hunt anything the size of a deer or larger, the AR-15 5.56mm is a wimp rifle. It is suitable for varmint control (prairie dogs and groundhogs, for example, which endanger cattle due to their burrows, and coyotes which have become a danger to people's pets on the East Coast where I live) and sport shooting. It is also a very good home defense weapon, since it 1) definitely does stop a human attacker very effectively, but 2) the small, light bullets it shoots don't tend to overpenetrate as much as typical handgun bullets or shotgun buckshot, meaning there is less risk to others in the home or even neighbors.