Hi,
On this website, the add to cart button is still in the products' HTML.
However, there is some CSS code to set its "display" to "none".
So, you don't see the add to cart button in your browser, but it is still here and a crawler looking at the HTML of the page will still see it.
The update to the 6.0.0 that was done there will help reduce the amount of new carts created by bots.
Note that if you already have a lot of carts in the database, it won't be as effective at preventing crashes of the cart table. You should empty the hikashop_cart and hikashop_cart_product tables once via PHPMyAdmin for that.
However, if you don't plan on allowing non logged in users to add products to the cart, a better solution would be to remove the prices displayed to non logged in users and making sure the "display add to cart button for free products" setting to be turned off in the HikaShop configuration.
That way, it would be impossible for bots to create carts. And if you still want to display a price to non logged in users, you could do so with a custom product field.