JEM 2.3: why we had multicat?

Long, ling time ago we discussed the reasons for multicat. I don't remember anymore and a tually I don't use and need it. So I feel free to reopen this discussion! Which are reasons to use this?

1 reason can be that when you have a event you can attach it to several categories and when there is a change you only have to modify 1 page.

Have to say that in my case i also don't use it and am not going to link multiple cats to 1 event. Maybe i'll add an option in my custom test version where you can simple copy the event to several categories. So that in case that i do want to have it linked in several categories it can be done.

Another reason for multicat might be the registering/attending part. When attached to multiple cats there is 1 eventpage.

Ah well there is a tag system in joomla and multiple tags can be added to 1 event.

I use multiple categories for displaying in different modules different events.
E.g. his event is normally in the category "general" but some of them are in the category "livestream" because they are streamed on youtube.

@Egnarts: I am asking this, because multicat seems to give big problems in programming. So there the question: how would it be possible to manage it in an other way?

Edit:
I took a look into the database structure. The table jem_cats_event_relations represents the relations between events and categories. Its correctly implemented like databases have to be.
What are the "big problems" on implementation?

@bluefox ?