Every company has a hierarchy, formal or informal. Further, that hierarchy almost always gets more formal as the company gets bigger. Based on that, the question is when, not if. The when comes down to: could you get more done with more than one person whose chief responsibility is to manage as opposed to work? If yes, add a second boss, if no then hold off.
One thing companies do that sort of works is to strip managers of certain formal powers, so that they have to lead without hanging vacation time, expense approvals, etc. over someone's head. Big tech companies seem to do this quite a bit, less so in other industries where regional/geographic heads are king.
A great deal has been written on this, but the reality is that in very few companies does it make sense to "innovate" on hierarchy. And even then, isn't it easier for everyone to understand the hierarchy if it is formal? As opposed to "carefully survey the room and see if the CEO can be challenged on this or not" and "realize that this is a CTO-only decision so run it by them first to protect yourself so as to avoid what happened last time you made an architecture decision on your own" lessons popping up all over the place.