Calendars suck for "people resource planning" in anything other than a trivial teamsize.
Can't control how many leave entries put in on a day,
Can't add up total leave days over a year,
Can't ensure that min levels of various skill levels within team. language, technology, etc.
No auditing of versions to see who changed what.
Excel can do all of that and push publish to HTML. We had a page a week 3 teams 50 people diary/resource plan that showed all the skill levels with green/amber/red highlighting.