I don't know for sure, but my guess is that each location that wanted to use sharding wanted to use it in different ways, ways in which LR did not allow. I also think it imposes other issues with indexing, etc, but these are all guesses.
I think you can still use DB-level mechanisms to support sharding (i.e. I think Oracle has a way to shard a table yet make it seem like one table to consumers), so you may have options there even though the logical sharding might have been discarded.
