Custom Post Type Like Event

I am having a hard time wrapping my head around this idea of separating the theme from the plugin. What I want to do is create a theme that has a box which some call a Megatron that shows events. I want it to have the featured image in the back ground and the title and excerpt on top. I have this working with post that have the category “event” assigned. My problem is the post type does not have the date feature of a true event. I have searched for a plugin that creates event that I can then use in my home page, other that just a list or calendar.

I have considered creating my own solutions. This is where I am very confused. Because all the advice says a theme should not create a custom post type; a plugin should. But then the themes can’t seem to handle these post type as like a standard post. If I create a custom post type in my theme then all I have to do is add a single-my_custom_post_type.php and use the WP_query to call the post for my Megatron. With the plugin that is not so. The theme has to be modified to handle the custom post. I know I sound lost, because I am and that is why I am writing this.

I found a plugin that does many of the things I need, but it requires a theme created for that plugin, but then what is the point of the plugin if it is limited to a theme dedicated to it? Isn’t the point of creating a plugin so that it can working almost any theme?