The Short Version
The ~27% figure is directionally plausible but overstates the certainty and universality of the underlying evidence. It appears to derive from a single self-reported developer survey (DX Newsletter, Q1 2026) across 500+ organizations, with no disclosed methodology for how "authored or substantially shaped" was defined or measured. Other available data points use incompatible definitions — "code written," single-company disclosures, or broader global estimates — and range from 25% to over 50%, making any single number highly sensitive to measurement choices.