https://en.wikipedia.org/wiki/Google_Chrome#Manifest_V3_2

> However, DeclarativeWebRequest is limited in the number of rules that may be set, and the types of expressions that may be used.[336] Additionally, the prohibition of remotely-hosted code will restrict the ability for filter lists to be updated independently of the extension itself. As the Chrome Web Store review process has an invariable length, filter lists may not be updated in a timely fashion.[337][338]

Is that not true?

It is, but it’s not relevant. Firefox offers both APIs.