First, let's be clear about something...my originaal comment was challenging the article's assertion that they only had a "sole purpose". That's their quote. If you believe that words still have meaning, then you should understand that "sole purpose" means "one and only one purpose". So I don't need to name 6 other purposes, I just need to name 1 other purpose. But I'm going to smash your naive challenge anyway and give you multiple.

1. From the perspective of the people who built them (the manufacturer), the "purpose" is to sell guns, not to kill as many people as fast as possible. They build what is popular and likely to sell.

2. For the vast majority of people that buy them, the sole purpose is to sit in a box or a case and never be used. People largely buy them the way they buy insurance policies. You buy an insurance policy because if you need it but don't already have it then the consequences are catestrophic. So this is just people getting it before they need it hoping they never have to use it. The reality is that most people just buy them to have them without ever using them.

3. Recreational shooting (not to be confused with target/practice shooting). The modern AR15 is just a fun gun to shoot. This is one of the most common uses. What makes it so much fun? The action is usually very reliable, you can shoot a lot before having to change or reload magazines: It's got the perfect amount of recoil - you can feel it but it's pretty light. Ammunition, compared to other firearms, isn't cheap but also isn't super expensive, and it's also a popular enough cartrige size that it isn't hard to find. It's lightweight and has great balance. It's just a very fun gun to recreationally shoot.

4. Marksmanship and Training (target practice). This is another very common purpose. The AR is well suited to this because of how modular it is. As a platform, it can accommodate a large number of accessories and has a lot of options. Example: longer heavier barrels with more riflings for better distance accuracy, a wide variety of scopes and sighting devices, many options for different sizes and shapes of stocks to accommodate the needs of the owner.

5. Hunting (animals). This is a common use. It's popular because it's relatively light (which means it's not a huge burden to carry it all day hiking/scouting), it's a large enough caliber to be useful for a wide variety of hunting, and because of #4 above, it can be modified to fit the need of the hunter.

6. Defense (against potentially dangerous animals). This is a common use case for me. I do a lot of trekking in the mountainous wilderness of the pacific northwest. I do occasionally come across mountain lions, bobcats, black bears, and even occasionally bull elk/moose who can be aggressive toward humans during some parts of the year (like during mating season). I've never had to shot an animal in defense yet, but I have had to discharge a round on many occasions to de-escalate a close encounter.

7. Defense (against potentially dangerous people). Related to #6 above, an unfortunate part of the modern world affecting our beautiful wilderness and forests. While out experiencing our great natural wilderness, I have come across many illegal marijuana grows in the middle of our state and national forests. I've also come across many inactive or recently vacated meth operations and even one active one. You obviously don't engage, and you get away as quickly and quietly as possible, but there is a very real threat to your own life when coming across something like this. I would not consider not being armed for these scenarios.

8. Show of force. Next to #2, this is probably the most common purpose. To be worn/carried and displayed as a show of force without ever actually being used. People go into a frenzied panic just at the sight of a modern AR15 (I mean, just look at you, your comments, and the comments of a lot of other people here just upset they exist). This is the actual most common use case and fate for a lot of these firearms...just carriedd and displayed as a show of force without ever being used to "kill as many people as fast as possible".

9. Building/assembly. This is an aspect that a lot of people really enjoy - the building/tinkering aspects of the platform. There are so many internal parts and so many parts options, and a lot of people just like to start off with a registered lower receiver and then spend a lot of time thinking about the build, acquiring the parts and then building it out exactly as they intended...only to disassemble/reassemble for the pure enjoyment of it. It's a bit like modle building, only instead of plastic or wood you have the feel of the metal, the sounds of the action moving andd sliding, the smell of the lubricating oil. This is a very common and popular use case and a lot of these are disassembled/reassembled more than they are fired. This one also appeals to me...probably thanks to all the time I spent in the US Marine Corps doing this and now it brings me a sense of nostalgia and is a very pleasant activity for me later in life.