IMHO, this is not the point. The core problem is that they're building systems that will remove competition altogether. You may still get your current systems

IMHO, this is not the point. The core problem is that they're building systems that will remove competition altogether. You may still get your current systems to market ahead of your competition, but future "competitors" will be built off of your data and Atlassian will be one more company in the list of companies profiting from everybody else building systems using their data, probably destined to fail because everybody else can do it just as easily, but the money required to fund Atlassian's systems that built it for them, however large or small, will have already been sent. Those systems that Atlassian will profit from will be built from the data of "customers", who also paid Atlassian will giving up their own data. With almost zero control over whether or not this happens (politically or individually), the only reasonable action to take is "take advantage while there's an advantage to be had".