This article revisits, extends and interrogates the position advocated in Honeybone (2019) — that phonotactic constraints are psychologically real phonological entities (namely: constraints on output-like forms), which have a diachrony of their own, and which can also interfere with diachronic segmental change by inhibiting otherwise regular innovations. I focus in the latter part of the article on the role of one phonotactic constraint in the history of English: *Rime-xxŋ. I argue that we need to investigate the emergence of such constraints in the history of languages and I show how this particular constraint, once innovated (which occurs through constraint scattering), can be understood to have inhibited the patterning of ash-tensing in certain varieties of American English (and also that it may now have been lost in some varieties). To do this, I adopt a phonological model which combines aspects of Rule-Based Phonology and aspects of Constraint-Based Phonology, and which is firmly rooted in the variation that exists when changes are innovated. Finally, I evaluate the extent to which the type of phonotactically-driven process-inhibition that I propose here involves prophylaxis in phonological change (I show that it doesn't), and I consider the interaction of these ideas with the proposal that all change occurs in language acquisition (‘acquisitionism’).