Why does everyone want Nook Miles Tickets?

Why is there such a high demand for Nook Miles Tickets? Are they a necessary aspect of the game's economy, or is it just a trend? How do players typically acquire them, and what benefits do they offer? Is there a limit to how many can be held or used, and are there any drawbacks to having a large number of them? Additionally, have there been any changes or updates to the system that have impacted their value or desirability?