It is much deeper than that. The incentives for advertisement are misaligned between the user and the service provider. Cloudflare is akin to Apple in this regard where privacy is feature, not a bug for their business model. Google can engage in their core advertisement business or they can provide cloud services and Business apps. Not both. It's like hiring a security guard that also has a second job of stealing what they're guarding.
But to OPs point, their incentives are not aligned with advertising. Cloudflare is not incentivized to sell user data or misuse data for targeted ads or mining data.
If they start selling data they gather as a result of their product they will burn user trust and goodwill in a single day and seriously harm their business and brand. So they would never do it intentionally.
