Calibri was a big deal when introduced because, along with the other fonts in that cohort[0] (like Consolas), it was optimized for subpixel rendering (known on Windows as ClearType), which was a new thing too, and made huge difference in quality and comfort of reading text on flat panel displays. It was a good, practical reason to create new set of default fonts.

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[0] - See: https://en.wikipedia.org/wiki/ClearType#ClearType_Font_Colle...

I always liked that they all began with 'C'. Made it easy to remember which were the default fonts that would be available on any Windows system.

Compare this to how Apple introduces San Francisco: https://youtu.be/OpveNRh-jXU

Call me old fashioned but there's only one San Francisco[1] to me. (Modern recreation[2] for current use.)

[1] https://fontsinuse.com/typefaces/31774/san-francisco-1984

[2] https://www.kreativekorp.com/software/fonts/urbanrenewal/