There's a gazillion of companies outside UK legislation; if they only went against companies doing fingerprinting, only those subject to their legislation would refrain from doing it
That argument works better against having Google be the enforcer than in favour: Google's rules are (as I understand it in this case) global, why should the UK's rules be made to apply to, say, a Japanese-language-only app sold only in the Japan?
(For all I know Japan has similar rules, the point isn't the specific country, but that this would be the UK projecting power internationally that it shouldn't be).
Google can choose to only have it against the rules for adverts served to UK (or UK and EU and any other country with strong privacy laws), and still have better ability to target the bad actors (as they can choose to either fully ban, or just ban from advertising to those countries, any company that breaks the rule regardless of whether they're in or outside ICO's jurisdiction).
(For all I know Japan has similar rules, the point isn't the specific country, but that this would be the UK projecting power internationally that it shouldn't be).