The QBS project has reached a developmental stage where it allows you to build Qt Creator projects without difficulty. Therefore, the project deserves the version number that would reflect its benefits to a large number of external users.
Why use QBS?
QBS itself takes care of setting up the build environment and allows you to build projects for different platforms from the same environment.
Allows you to build parallel multiple configurations of the project.
This question comes up often. Despite the fact that it is possible to replace the existing build system based on qmake, configure scripts and the infamous synqt still cannot be thrown out. Therefore, there will not be much confusion from QBS. The developers are aiming higher and also want to replace configure with syncqt, and this is where QBS is still underdeveloped. In addition, the assembly on a clean system (bootstrapping) is not yet possible.