I didn't say it's impossible, but imagine you are hunting or fighting and pursuing an enemy or prey and your ally is out of arrows following you. You want to drop some of yours because your ally is already following you, so you open your inventory and drop half your stack as fast as you can. But you cannot continue running right away because in the flurry of activity you stopped in front of a little hill, where you have to jump upwards one block and pick them right back up.
Even if it's hardcoded, it should be possible to distinguish between - let's say - loot and dropped items and add a flag or something. I don't say it is absolutely necessary, just nice to have.