For one example, say you were making voting-booth software. You really don't want a (hidden) timestamp attached to each vote (much less an incrementing id) because that would break voter confidentiality.
More generally, it's more a underlying principle of data management. Not leaking ancillary data is easier to justify than "sure we leak the date and time of the record creation, but we can't think of a reason why that matters."
Personally I think the biggest issue are "clever" programmers who treat the uuid as data and start displaying the date and time. This leads to complications ("that which is displayed, the customer wants to change"). It's only a matter of time before someone declares the date "wrong" and it must be "fixed". Not to mention time zone or daylight savings conversions.
But there are cases where it matters. Using UUIDv7 for identifiers means you need to carefully consider the security and privacy implications every time you create a new table identified by a UUID, and you'll possibly end up with some tables where you use v4 and some where you use v7. Worst case, you'll end up with painful migrations from v7 to v4 as security review identifies timestamped identifiers as a security concern.
This doesn’t even rely on your system’s built-in RNG being low quality. It could be audited and known to avoid such issues but you could have a compromised compiler or OS that injects a doctored RNG.
However, because the online ordering system assigned order numbers sequentially, it would have been trivial for that company to determine how important their business was.
For example, over the course of a month, they could order something at the start of the month and something at the end of the month. That would give them the total number of orders in that period. They already know how many orders they have placed during the month, so company_orders / total_orders = percentage_of_business
It doesn't even have to be accurate, just an approximation. I don't know if they figured out that they could do that but it wouldn't surprise me if they had.
