They may not be paid by the hour, but they're being graded by the hour.
It may be beneficial to the company to save overall "company time" at expense of wasting time for many individual employees, but I don't think this analysis accounts for the costs of people leaving or being fired. Both of those are very costly, but they're step changes and hard to attribute to any specific cause.
The above poster was fairly obviously using a figure of speech, they did not mean that there was a specific formal evaluation like a mid-year review every hour.
Think about what the average salaried person (especially outside of tech) might get dinged on either explicitly or implicitly.
Come in at 10:00 every day? Not being "seen" enough in your seat or around the office? Not replying quickly enough in Teams/slack? Jira/Github statistics? These are not things that do not reflect a salaried worker's output but you're still getting evaluated by them on an minute by minute, hour by hour, day by ay basis.
But surely you experienced the fact that being paid a salary is a matter of contract, while being evaluated (formally and informally) for productivity is not independent of time. The company may find it valuable on the net to waste your time with distractions and bad process, but your manager may not know it and think you're just lazy.
I have certainly experienced management that took many actions which reduced productivity.
I think the biggest blind spot is management's negative emotional externalities which cost far more than anything else. Many of us got into this because we love it, let's us sincerely do our job well, please!
It may be beneficial to the company to save overall "company time" at expense of wasting time for many individual employees, but I don't think this analysis accounts for the costs of people leaving or being fired. Both of those are very costly, but they're step changes and hard to attribute to any specific cause.