[jabiko]

The browser could check whether the cursor image would be painted outside the page viewport.

In this case the browser could create a clipped version of the cursor image and set it as the new cursor.

[Mithaldu]

That would be very expensive computationally, and as seen in the padlock, accompanied by latency and jitter.

It would also break the case where pages have legit uses for crosshair style cursors, or cursors that are rotated 180° in order to not overlay contents.