Even if I get up to go to the bathroom, refill my water, and get another cup of coffee 4 times a day, the point is still valid. If there is no coffee provided by the company that means I either 1) go without, or 2) have to venture out of the office to find it.
In many areas leaving the office for just about anything means taking the elevator downstairs, walking through a sprawling parking lot, making a 10 minute drive to the nearest Starbucks, spending 5 minutes in the drive thru, and then reversing the whole process. I could probably justify that once a day, but upwards of 30 minutes per trip is going to be a really hard sell any more than that.
Even as a freelancer who has no one looking over my shoulder and who works from home I'm simply not going to do that - I bought a coffee maker. Take that to the far opposite extreme and consider the call center employees who have hard stats for their productivity every day and have scheduled breaks... there's simply no way they _could_ do it, even if they wanted to.
So yeah, maybe it's an indicator for _some jobs_ of a poor work quality, but that was the entire point - it's a cheap and easy way to improve that work quality.