They all have their issues. Maybe the crux of it is chat. If your work is integrated into your chat — the day to day online social space — it’ll feel “integrated”
With Apple their are not going after Safari and whatever integration - they are embedding stuff into OS across the devices. It helps that they have their Apple One subscription and cloud drive integration. Also MacOS, iOS connectivity etc. Search across all your devices and files, analytics.
With Microsoft the whole Office 365 integration is extremely tight - share files, use analytics dashboard, integration with sharepoint, outlook and calendars and so on.
Just like with GCP and other Google's offerings - they are good separately and people are fine using them independently. But they don't work nicely together.