Yes, local leagues will often come up with their own rules in regard to sliding. Some might prohibit slides, some might require them. Those rules are just that- local rules. The standard rules of softball never require a runner to slide.
This is personal opinion, but my feeling is that the standard rules to avoid contact- if the coaches are teaching the players their responsibilities on such plays, and the players are abiding by those rules, and the umpires understand how to enforce them- provide a good balance of fairness to both the offense and defense and work best to prevent collisions and injuries.
For those leagues that add special rules requiring players to slide, in the name of "safety", I will point out that more injuries are documented due to sliding than any other baseball or softball related activity. More than batters being hit by pitches, more than fielders being hit by batted balls and more than collisions between players.