customId just call it ID, that way we can force users to work a certain way a bit more than give the impression that they can apply any id necessary. I think it would be most beneficial to keep the same way discord/discord.js handle id's than leave it to the user. Just for the sake of consistency MessagePrompter or PaginatedMessage are a prime example of what users expect to be handed when trying to create a paginated message or something else. Instead of writing their own collectors (this is just an example on those 2, not on interactions itself).