Context: was looking for a decent service to give me a calendar a little while back but one thing that kept stopping me is there seems to be absolutely no service that just offers you a nice calendar, its only email services that happen to offer a calendar on the side.
I don't want another email. I have enough, and my current one is tied down to gmail (but I'd prefer if my calendar wasn't).
I'm sure there must a historical reason for this, but also why is does it still persevere?
One is a scheduling and time management thing, the other a communication system. I don't need to sign up for a messaging app to have a todo list.
Your calendar app integrates with your email app. So when you create a calendar event and want to invite Bob to it, you can use your email contacts to find Bob. When you send the invite, it goes by email from your email system to Bob's. When Bob opens it, his email app asks him if he wants to add the event to his calendar.
Your calendar app and Bob's calendar app never talk to each other directly, but you're still able to invite Bob to an event. Your calendar only talks to your email. Your email talks to your email service, which talks to Bob's email service. Bob's email client talks to Bob's email service and then to Bob's calendar.
This is actually good. It means that anyone can switch to a different email or calendar app and all they have to do is update their contacts. People can use Hotmail or Gmail or Microsoft or self-hosted email, and integrate whatever calendar they like alongside it.