From the paper introduction, about the limitations of existing methods:
> However, over the last few decades burnout measures have been shown to have some limitations, including differences in the conceptualization of burnout being measured (exhaustion-only or multidimensional [e.g., including cynicism, professional efficacy]; see Guseva-Canu et al., 2021 and Schaufeli, 2021), the prescribed factor structure, which remains unclear (three-factor vs. two-factor; e.g., Worley, Vassar, Wheeler, & Barnes, 2008), the apparent divergent role of professional efficacy (e.g., De Beer & Bianchi, 2019), and the inability of these measures to provide a global burnout score as is ideally required when measuring a syndrome (Schaufeli, Desart & De Witte, 2020).
What they decided to do and what is novel about it follows right after:
> Due to these afore-mentioned limitations, Schaufeli, Desart, and De Witte (2020) endeavored to create a new instrument, the Burnout Assessment Tool (BAT). The development of the BAT is unique in that, unlike the development of other burnout measures, both inductive and deductive approaches were used to decide on the final list of items included in the survey. The specific inductive approach employed by Schaufeli and colleagues is uncommon, because the Dutch authorities acknowledge burnout as an occupational disease, and therefore experts who have experience working with (and categorizing) these patients could be interviewed.
It doesn't mean it's enough for you to think it's novel but at least that's why they think it is.