This has nothing to do with security and everything to do with banning tools like youtube-dl, wget and others; from the post:
> The browser must identify itself clearly in the User-Agent. The browser must not try to impersonate another browser like Chrome or Firefox.
> The browser must not provide automation features. This includes scripts that automate keystrokes or clicks, especially to perform automatic sign-ins.
Edit:
I feel like mentioning youtube-dl was a mistake. It's not just about youtube-dl.
This policy bars the use of all text-based browsers, headless browsers, browsers without javascript, and browsers with automation when accessing Google's services. It bans browsers that contain Node.js, even.
> The browser must identify itself clearly in the User-Agent. The browser must not try to impersonate another browser like Chrome or Firefox.
> The browser must not provide automation features. This includes scripts that automate keystrokes or clicks, especially to perform automatic sign-ins.
Edit:
I feel like mentioning youtube-dl was a mistake. It's not just about youtube-dl.
This policy bars the use of all text-based browsers, headless browsers, browsers without javascript, and browsers with automation when accessing Google's services. It bans browsers that contain Node.js, even.