Not only writing and printing is hard, so is selection and moving your cursor. Because in most tools, the right and left arrow keys don't mean right and left in Arabic, Persian etc. It's reversed in RTL languages, so right arrow moves the cursor to end direction (left in LTR, right in RTL) and left arrow moves you towards start direction (right in LTR, left in RTL). So in bidirectional text, for example when majority of the text is English and you have a short RTL phrase, you are holding right arrow and then then when you reach the RTL part the cursor suddenly jumps to the start of RTL text, then it goes to left and it SEEMS like you are going backward to the start, not forward. That is until you reach the end of RTL phrase and you teleport to start of next LTR part.