This is outdated info for the UK, may still apply to the EU. The blog appears to be from 2021, so this is not surprising.

In the UK the ICO have updated the 'cookie law' to allow for non-consensual analytics tracking under the statistical purposes exception.

https://ico.org.uk/for-organisations/direct-marketing-and-pr...

The trip up point will be that businesses sending emails to individuals still need to provide a method by which users can object to the tracking. The tracking itself is fine though, as tracking pixels in emails are all for statistical purposes.