There has been a surge of syntactic research on compounding, joining a large literature on the nature of roots and phase theory. In an attempt to probe into the syntactic domain for idiosyncratic interpretation and to account for lexical integrity effects, some recent studies on compounding have argued that root compounds are made up of two free acategorial roots directly merged in syntax, without undergoing categorization. The main goal of such an approach is to extend the phase domain in order to maintain two uncategorized roots awaiting further Merge operations. When a category head is merged on the top of this compounded structure, it will trigger its Spell-Out, and as a result, both roots will be identified as a single syntactic object for the purposes of movement and binding, and will be assigned a fixed, non-compositional interpretation. In this article, we argue that categorially non-individuated roots are not legitimate LF and PF objects, alongside Panagiotidis (2011, 2014, 2015). Consequently, any syntactic object made up of two or more uncategorized roots will induce formal crashing at the interfaces. We claim that root categorization cannot be analyzed neither as a matter of parametric variation, nor as an optional derivational step. Additionally, we propose that lexical integrity effects can be straightforwardly accounted if we assume that the unifying characteristic of compounds is the presence of a category head merged on the top of two categorized roots. Finally, we claim that non-compositional domains are not determined by categorization. Rather, non-compositionality is assigned at LF, through a set of LF instructions associated with roots in a particular syntactic environment.