This seems to be fundamentally based on n-grams and manually built regexes. "Slop", or more narrowly annoying -isms and model stereotypes, is not just repetitive n-gram sequences, mode collapse manifests itself semantically. Sometimes repetition/stereotyping is desirable (you need semantics to understand if it's the case), and sometimes undesirable repetition is undetectable by n-grams and regexes, especially in languages that rely on word formation. Fixing the mode collapse probably needs a sufficiently powerful reference model of semantic diversity, which doesn't currently exist.