I'll simply raise the question here "You have to have playmakers" ... to do what?
Everything is relative, from player talent to levels of success. We are probably 2-4 levels short of what we need to compete. My sense is that discussions like this tend to shift levels. We know we need to break the losing habit. We'd like to flash to a Super Bowl ala '99. But there are several levels between the two.
To be a perennial contender and win titles? Yeah, you need playmakers. But for me the first task is to become competitive on a weekly basis.
To do THAT ... I don't know how many "playmakers" a team needs. But then, the term is itself relative. I assume you are referring to transcendent players who can make astonishing plays. Yeah, champion teams have some. We actually have one in our DL. But no team has more than a couple.
And in my view, you can get to competitive levels of success without many transcendent players. You do need players to make plays. But, again, in my view, good coaching can put players in positions to make big plays without transcendent levels of talent. A great WR for example makes the impossible catch. A good WR, however, can run a good route, read the play, and get open for completion at a big moment that turns the game. Great WRs can do it more often, but, again, every year we see players known for making plays change teams and stop making plays. And we see the opposite.
For me, the proper framework to apply is that of the ceiling and floor. To play near its ceiling, a team has to make plays at its level of capacity. And I believe coaches do a great deal to maximize players', units', and teams' play making abilities. That's how a coach's effectiveness should be measured. How well does the coach lift a team to play near its ceiling?
In the NFL, I believe all teams have enough guys who can make plays to be competitive each week, and win their share of their games. Most teams have enough to snatch a couple extra games and get over .500 and into the playoff conversation.
Good coaching sustains a team at competitive levels and at the top of its ceiling. Good coaching establishes and maintains competitive discipline and thereby wins games.