Google's official webmaster channel on Twitter responded to a question about the ads.txt file. Someone asked if you need it for SEO or search because he sees GoogleBot trying to access it. The answer is no, you don't need it for Google Search or SEO.
It is somewhat needed for Google AdSense but not Google Search.
Here is what Google said on Twitter, "The ads.txt file appears to be related to @AdSense - it's not required for Google Search."
The ads.txt file appears to be related to @AdSense - it's not required for Google Search. https://t.co/2qBm7Kng4j
— Google Webmasters (@googlewmc) December 2, 2019
The folks at AdSense are pushing you ad this file but again, this is specific to AdSense and it is a "IAB initiative that helps ensure that your digital ad inventory is only sold through sellers (such as AdSense) who you've identified as authorized."
But again, it is not required for SEO or search and if you don't have AdSense or other IAB related ads on your site - it is not needed at all.
Forum discussion at Twitter.
