I call bull.
Following this idea means I need to buy multiple pairs of pants so I can wear them with each height of shoes. After all, two inch heels would need a different hem from three inchers. It also means that any heels I bought with cute details will be almost entirely covered. Stilettos will catch on the hem as will platforms. I've seen this idea expressed several places, and the argument is that hemming them shorter will make you look short.
Other people say that the hem should fall mid-arch or with the hem just skimming the vamp of your shoe. For flats, this comes to, yes, about half an inch off the floor, and for heels this at least means you won't have to hem for each heel height. Plus cute toe details of shoes would always be visible. That's more doable. However, I can't shake the feeling that a heels/flats hemline is yet another thing imposed on women's dress because it's nonsensically based on men's attire.
How do you have your pants hemmed?
Very long pants from Victoria's Secret.