I'm a keyboard addict. Partly because my wrists and fingers don't like working with a mouse.
Using the cursor keys to move through text on a page, is highly frustrating.
For example, the text cursor disappears when using the down arrow reaches the end of a bulleted list.
Another: using the down arrow often moves the cursor to the end of the last line in a paragraph/block before moving to the next paragraph/block. This is unexpected and breaks my flow.
Third: Using the right arrow at the end of a paragraph/block does not move to the beginning of the next paragraph/block. Analogously, using the left arrow at the beginning does not move to the end of the previous.
There are other examples, but the above are what I've experienced most frequently.