Theorizing on dual- and multi-tasking has not made much progress since the early insight of Telford (1931) and Welford (1952) that response selection may represent a bottleneck in human information processing. A closer look reveals that the questions being asked in dual-task research are not particularly interesting or realistic, and the answers being given lack mechanistic detail. In fact, present theorizing can be considered mere empirical generalization, which has led to merely labeling processing bottlenecks rather than describing how they operate and how they actually produce the bottleneck. As a template for how to overcome this theoretical gap, the Theory of Event Coding (TEC) is applied to dual-task performance. It is shown that TEC, which has not been developed to account for, and has not yet been applied to dual-task performance and its deficits, can nevertheless easily account for the key findings guiding resource and stage theories, while making the underlying mechanisms explicit and transparent. It is thus suggested to consider multitasking costs a mere byproduct of the typical functioning of the cognitive system that needs no dedicated niche theorizing. Rather, what is needed is more mechanistic detail and a more integrative account that can deal with findings related to both resource theory and stage theory.