I think it's the <current year> meme. Just how for a while every JavaScript library had to end in .js, and before that when every electronics manufacturer put an i in front of product names until Apple stopped them. Another example is libraries being described as "blazing fast" or "minimal".
It's easier to google something like "CalendarJS" rather than just "Calendar," which could give you anything but the JS library you're looking for. I think it’s simply practical.
It's basically bankrupted creativity.