What are you talking about?
Of course it’s mentioned on the store page. What that has to do with anything? ‘Bonus’ is not a description of something unannounced and unlisted.
I’m talking about its status and relation within DLC and to 2DE in general:
PLUS 1 new longtime fan-requested civilization for use in standard Age of Empires II: Definitive Edition:
It is a bonus, something separate added alongside the DLC itself- which is a SEPARATE set of 17 civs from ancient-themed previous installment, AoE1. This is NOT expansion of 2DE, it runs off that game*
It’s not a core feature. It’s additional bonus content that made its way to the base 2DE, alongside core feature which is mentioned AoE1 civ pack.
Just because there’s ‘Rome’ in title doesn’t mean the Romans are the focus of this DLC. The focus is AoE1.
*as a separate ‘rule set’ civ overhaul, as switchable application mode from the main menu, as even a standalone product listed in the library- I don’t know the final form of this and it doesn’t matter. 99% of the content is self-contained, cohesive, and Romans are added on top and outside of that AoE1-themed experience pack.