Magento 1 was past end-of-life: no patches, an aging integration surface, and a storefront whose structured data predated everything AI engines now read. On mobile, category browsing ran at 600ms-plus INP. Add-to-cart behaves the way you’d expect at 600ms. Customers left.
Whether to replatform wasn’t really the question — the platform had answered it. The question was whether the new stack would just be newer, or become a foundation the catalog and AI-search work could actually compound on.