I think they still matter, but we don't have anyone who can run (except hurt people) and we can't throw anybody out.  Other than that - they still matter.

If a person is standing at First, steals Second and scores on the next single, they count.

If a person is standing at First, does not steal Second and  does not score on the next single, they count.

 

The 75% success rate requirement doesn't factor how a proven stealing threat impacts the pitching strategy while on base, does it? It's just looking at the increased or decreased win likelihood from the event, itself, Meanwhile, with a stolen base threat at first base, a batter gets a higher percentage of fastballs and fewer chase pitches that the catcher might have to go down to block. The resulting greater OPS in those situations would also be a benefit. Someone should attempt to quantify that.