"Don't mess with markets" is easy to understand. That said people are perfectly willing to mess with them in ways both large and small. Sometimes they have a

"Don't mess with markets" is easy to understand. That said people are perfectly willing to mess with them in ways both large and small. Sometimes they have a guiding maxim and sometimes they just say it's a self-evident action that will outweigh any downside. I suspect the truth is that in both cases it comes down to who is going to benefit - with it more likely to happen if the "who" is either a large number or a small number with a lot of influence and the "benefit" is something that's immediately apparent to the winners and not immediately apparent to the people who lose in the intervention.