How proprietary formats have become Microsoft’s main tool for lock-in

Microsoft's proprietary document formats (DOCX, XLSX, PPTX) create vendor lock-in by design, making documents inseparable from Microsoft Office software since their specifications contain undocumented features that only Microsoft's applications can fully reproduce. When users try to open these files in other applications, formatting distorts and layout shifts, effectively trapping users in the Microsoft ecosystem despite open standard alternatives existing. This lock-in mechanism demonstrates how proprietary formats—rather than technical bans—concentrate power in a single company's hands and discourage switching to competitors.