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, and add-to-cart behaved the way add-to-cart behaves at 600ms: customers left.
The decision wasn’t whether to replatform — the platform had made that decision itself. It was whether the new stack would just be newer, or would become the foundation the catalog and AI-search work could actually compound on.