That’s a very Linuxy thing to do. The devs allow you to do whatever you want. If you want to have several 4K displays and find your cursor by shaking it, go right ahead. If you want to cover the entire display with a massive cursor, be my guest.
Microsoft and Apple seem to love limitations, whereas FOSS devs want to give users the freedom they deserve. Besides, there’s a valid use case for many things that would seem completely absurd to you and me. The devs can’t know what kind of weird situations the user have, so “sensible limits“ would only end up being infuriating.
That evaporation rate is so small that you can think of black holes as eternal. However, it’s still not zero, so in extremely long time scales, it begins to make a deference. That’s when the heat death of the universe comes in, but those time scales are just ridiculous.