They're probably talking about how a lot of the companies making HomeKit-compatible products charge a premium, whereas Aqara's products tend to be very reasonably priced. So you may not need to buy their hub, but you may end up paying a lot more overall once you start buying several devices.
I'd love to have fewer hubs, but if the day-to-day usage is less reliable *today* compared to using another manufacturer's products that happen to use a hub, then I'll take the hub, thanks. For example, the Lutron Caseta products (e.g., light switches & dimmers) are known to be extremely reliable, responsive, and offer good range. Whereas, the devices that work via Apple's Apple TV or HomePod mini have typically used Bluetooth, which has poor range, often resulting in an unreliable end-user experience.