Replacing blocks with the new "summon FallingEntity" creates a drop even when doTileDrops is False

Well, yeah. That's natural. Why do you thing sand breaks when going through a torch? It doesn't have any room to fall in, as a torch is a block,

That's different, there shouldn't be any drops at all if doTileDrops is false.

You can avoid this by adding DropItem:0 into the data brackets, though I agree it should obey the gamerule.