This is why.

In looking at the images in the ChipGuide for the corresponding $25, $100 and $500 chips (the same artwork was used for the $5), the other denominations are noted as being issued in 2015. Moreover, TheChipRack reflects a 2020 date for the $5, it also shows 2015 as the issue date for the 3 other, matching logoed denominations.

Lastly, in looking at the Nevada Gaming Control Board's Historic Chip and Token Report, one can see that a $5 chip was released with an unspecified date, but just below it, there is a listing for the $25, and $100 versions with approval dates of 09/16/2015 (see image). The same design $500 was approved in 2014 (not imaged here).

Now, it is quite possible that the Chip and Token Report reflects an unspecified approval date for the $5, it was likely approved then, with the $25 and $100, and the casino may not have released the $5 chips until 2020, but that is doubtful. Perhaps TheChipRack authors know something not stated in the TCR. But the Chip and Token Report does disprove the 2010 date.

Accordingly, I will change ChipGuide to 2015.