I have never understood how the states could do this to themselves.
As I remember some of my history on that, a number of states for various state political reasons were very slow in replacing retring or deceased senators. There were constant claims that somehow this would reduce the railroads and other monopolies influence (bribes) in state legislatures. Seems to me all it did was reduce the number of points to “influence (bribe)” from many - the legislature to two - the number of Senators in the post-17th amendment system.
There may have been other reasons but those are two I remember.