Alright, thank you all for the replies! It's certainly something to get used to, but seems like an interesting approach overall.

https://i.imgur.com/tco5rwa.jpg

Just launched into a new game and immediately ran into this problem. When moving any item stacks from the inventory to the quickbar or within the quickbar, instead of removing the first one and placing it on its new position, the game inexplicably creates a new stack ...