Novel-prize winning economist Paul Krugman coined the term "zombie idea" to describe hypotheses that persist despite their incongruence with accumulating evidence. This concept provides a useful framework for re-evaluating the long-standing paradigm of ‘reticulate evolution’ in reef corals, which has been a dominant framework for interpreting coral taxonomy and evolution for over three decades. Influential syntheses proposed that widespread hybridisation and porous species boundaries fundamentally distinguish coral evolution from the classical bifurcating ‘tree’ model that characterises most evolutionary lineages. This hypothesis was primary driven by the inability of traditional morphological taxonomy to reliably delineate species, with observations such as observational evidence such as morphological intermediates, mass spawning, and shared haplotypes and discordant phylogenies in early phylogenetic trees frequently interpreted as evidence for reticulation. However, many of these observations are equally consistent with alternative evolutionary processes, including incomplete lineage sorting, rapid diversification, phenotypic plasticity and widespread convergence in morphological characters. The advent of genome-scale sequencing has fundamentally changed our ability to distinguish among these competing hypotheses. Here, we critically evaluate the empirical evidence underpinning the reticulate evolution paradigm, contrasting historical interpretations with insights from modern phylogenomics. Using recent case studies we show that coral evolution is not an evolutionary novelty, but largely congruent with the contemporary understanding of speciation and evolution in lineages across the Tree of Life. Although introgression occurs in some coral lineages, current evidence provides little support for pervasive reticulate evolution as the dominant framework for understanding coral diversity. We conclude the ‘reticulate evolution’ as traditionally proposed for reef corals is a zombie idea. These results highlight the importance of continually re-evaluating influential evolutionary hypotheses as new data and analytical approaches become available, and the importance of quantitative frameworks for developing a robust taxonomy that accurately reflects the diversity and evolutionary history of reef corals.