The only significant difference between 1.2 and 1.3 is the load times.This doesn't really affect the route in any way, and makes 1.2 obsolete/ 1.3 is unarguably faster. For these reasons, I disagree with you on this. It isn't that hard to update to 1.3, and runners can easily beat their previous records that would become top 300 (In your example). If, for example, there is a 6 second difference, the standings shouldn't change very much, as long as the runners perform at or near their previous record. The only difference would be the time, as long as most of the runners ran 1.3 (Which is factually better). Therefore, the standings wouldn't change that much, and the ones who do fall in the leader board are probably inactive members of the community, because they didn't bother to update from 1.2 to 1.3 to get that advantage. However, the 1.0 argument could stand, as there are minor differences that change the route.

The most accessible version happens to the be fastest. The version split is no longer necessary, especially since only a handful of runners aren't updating to 1.3.