Multi-values are great when all you need to do programmatically with them is either write the whole list in (e.g. a result of Filter()), and read from it, but not mutate the list. Adding (via ListCombine()) is okay and a justifiable approach when making a separate join table is more effort. But removing from the list is usually more work than tracking the relations separately.
Just for the fun of it, here’s list modification taken to extreme: To-do list, but it's just one table and one row 🤯 Definitely not an example to follow.