fun with payment due dates

wanted to change payment due date on a WF credit card, and learned the following:

https://retailservices.wellsfargo.com/customer/faqs.html

"the 3, 6, 10, 15, 19, 24, 26, 29, 30, and 31 of any month aren't available to select."

But that's not all! Their FAQ page lied. WF’s actual due date selection page actually further blacks out the 11, 14 and 25!

Which led me down the rabbit hole of comparing this vs other issuers.

Citi blacks out the 4, 5, 11, 12, 18, 19, 25, 26, 29, 30, 31. In a 7×4 grid, the first 8 black-out dates fall neatly into the 4th and 5th columns.

Amex blacks out the 8, 17, 24, 25, 26, 29, 30, 31. Interestingly, references to their date change webpage (itself still active) are scrubbed from Amex's website. Had to google it

US Bank blacks out the 2, 5, 8, 12, 13, 14, 18, 20, 21, 25, 26, 27, 29, 30, 31, for a total of fifteen days!

Chase only blacks out the 29, 30 and 31.

I can understand blacking out 29-31 because some months don't have them, but there doesn't seem to be any rhyme or reason to the rest. 25 and 26 are common outside of Chase; one would think it’s Christmas (nevermind the US doesn't celebrate Boxing Day), but if holidays need to be blacked out, why not the 1st and 4th?

WF and USB are especially egregious, with nearly half of the month blacked out.

Which begs the question…. why? This just all seem very arbitrary, illogical, and IMO pointlessly restrictive given the state of payment tech in 2026.