The problem with AMP email mentioned in the article is that it just appeared because someone on the gmail team wanted it. There was no process for getting it out, GMail as the dominant email provider strongarmed a few other providers into supporting it. All questions and discussions on AMP's github were shut down by the project leadership that would go on to write propganda pieces on how AMP development was open to everyone.

Just because there's some marginal benefit to AMP for Email, it doesn't make it good.