This is true for a one bucket or a two bucket system too. It's strictly more complex to have more buckets to possibly pay attention to. I don't know how you can possible argue otherwise.

But even if you accept that the three bucket system is no more complex than a two bucket system for many people who just focus on one number, some people have to actively monitor/plan around two at a time. I've definitely had years where it wasn't clear whether EQP or EQMs were going to be what got me over the line at the end of the year, so I had to think about a lot of my travel with both in mind.