First, branching/PRs are not automatically process-heavy. If it is for your company, there's probably something else wrong.
Second, this process—if done right—dramatically INCREASES code quality and DECREASES defects. This can be backed up with data. Code reviews, if they're not rubber stamps, are extremely valuable.
Third, the trunk-based model described in the article often leads to big-bang release branches. Master should be gold. This facilitates rapid and small releases, which directly impacts the business. This can also be backed up by data (e.g. see the Accelerate book).
Fourth, this model (again if done right), plays an instrumental role in compliance. The article doesn't even mention compliance, which is a HUGE thing bogging down a lot of companies trying to adopt DevOps practices right now. It has nothing to do with discipline or trust.