I don't deny this, but I think you can say this for any position that ultimately can deliver something. A good PM, a good IT manager, or just the accepted good engineer. People that really want to contribute will work on what matters most and set their egos aside. I say this as someone who has been a PM before and realized it was not the most critical function at the time, so I offered to go back to engineering (I've worked full time as both for years). A good employee will contribute the best they can, and a great employee will be able to identify what matters most and works towards helping (even if they can't do it themselves).
I realize my comment is a tangent, I just feel like it's unnecessary siloing that props up some positions as more important than others. It will depend on the situation. Sometimes you need more engineering talent, sometimes you need more salesmanship, sometimes you need more product direction - it's impossible to know without being at the company. And it's very hard to recognize what matters most outside of your area of expertise.
There aren't a lot of people that can make or lead a team to make world class products, but the number of marketing mangers who are exceptional enough to have significant impact on your company aren't that many either.
This is true of every field from doctors to lawyers to software developers. Most people are pretty average at their jobs.
On the other hand there is unbounded work where the skill level necessary is unknown and the costs of going with someone who is insufficiently skilled could be immense. For example odds are there's no way to know if your surgeon isn't up to the task before they've cut you open, which is a terrible time to discover that fact. For unbounded tasks it makes sense to always hire the best you can possibly afford, even for something that seems like it should not require much skill.