In Survival mode when mining a block with any items, for example a pickaxe, then switching to another items in your hotbar, while still breaking, restarts the breaking of the block. So lets say im breaking cobble with my pickaxe and accidentally switch to my sword, it will restart breaking the object and u would have to start all over again. Some people will start to find this really annoying (especially noobs). New people to the game might be trying to switch items while breaking and then being confused on what changing ur items on the hotbar does. All in all, most of us do NOT like this bug (or maybe a feature) and would really like it to be removed. Most players are used to changing items while breaking and would like it back to how it used to be Thanks!