When a cell is higher/wider than the screen then it is impossible to read anything that is outside of the screen because upon scrolling the whole cell gets "scrolled away". This is also annoying for cells that actually fit the screen because it disrupts the work-flow. Since Calc scrolls 3 columns each time when the scroll wheel of a mouse is used the user gets highly varying "scroll speed" with differently sized cells. With "partial cell scrolling" the scrolling speed would always stay constant and content of all cells, regardless of size, could be read easily.
I believe this one is a DUP of "Bug 34689 - UI scroll problem: Cell with dimensions exceeding screen dimensions impossible to work with" @Reporter: Please feel free to reopen this Bug if you find evidence that we have an independent issue here. Please start Bugs with Status UNCONFIRMED. *** This bug has been marked as a duplicate of bug 34689 ***