Knx is an open communication protocol developed in order to make the various smart devices of the house communicate with each other. Knx is not a brand and does not belong specifically to any particular manufacturer. To find a "smartphonic" comparison, KNX can be said to be like Android.
The protocol was developed by the "KNX Association" of the same name. Currently the association is in charge of verifying in its laboratories that all those who adhere to the strict standard imposed, both at the level of protocol support and at the level of data coding. This is because the determining factor in KNX is the complete interoperability between devices of different brands. The association maintains this system through royalties that producers have to pay to be able to brand their products as KNX.
Why do manufacturers do it?
Because they are thus able to access a booming market. This provides visibility and can allow customers to become loyal, thus also being able to sell other materials not strictly related to home automation. Furthermore, a manufacturer does not need to provide a complete home automation solution, but can focus only on some particular sectors in which he considers himself more expert and let the user operate the system using devices from other manufacturers.
Is it convenient for the user?
Of course it pays! It has the ability to access a lot of different products for a variety of applications. You can choose the ones you think are best, both on a technical, design and economic level, with the certainty that they will all be interoperable and interfaceable with each other.
Furthermore, the market is highly competitive: a new actor can always arrive, introducing a novelty or an improvement. This is an advantage for the user because he can obtain: higher quality devices for the same price, cheaper devices for the same quality or even a combination of the two options.