There are many “redundant” date situations, which I think should be kept (but not used) simply because, from a programming point of view, it is easier to keep the option there for when an oddball case needs it, than it is to remove it and then to somehow create a special use case for the oddballs.
For example - I am your father. In most cases, the dates are going to be “from birth” and have no end date because even after death I am still your father.
Most cases of dates would involve step fathers, I was your step father from 1990 until 2015 when I married/divorced your mother.
But, if you look at Nicole Richie, she has two dads because the 2nd dad adopted her. So both dads should have start dates, and one dad should have an ending date.
I founded “justcheckingitout records”, I founded it. A one time event. There is no “start” date, nor an end date to when I founded it, there is only a start and end date as to when I involved with the business.