For 2 and 3, office software and OSs have strong network effects and up-stack effects, just like CPU instruction sets.
Also, I'm sorry, but OSS office suites compete with Office and GSuite the way grocery store frozen pizza competes with Domino's and Papa John's. Quality and completeness of execution matter a lot in that category.
That was intentional - I think Office (or, uh, Microsoft 365 Copilot as it is now called) is frustrating mass-market mediocre software! That said, it consistently lets me do my job, while LibreOffice is often unusable for my purposes.
Also, I'm sorry, but OSS office suites compete with Office and GSuite the way grocery store frozen pizza competes with Domino's and Papa John's. Quality and completeness of execution matter a lot in that category.