It forgets that a generalist is always developing his/her skillset and forgets to account for the value of having a greater perspective. The key assumption being made is that a master is often needed. Depending on the subject matter having a master is often not needed and is like killing a fly with a wrecking ball.
To use an analogy of going to battle where neither sides have optimal resources. Quite an apt analogy for being a startup. Would I rather be a specialist and understand every tactic and use of hand to hand combat fighting or would I rather have wide scope of knowledge with an understanding of the ebb and flow of a battlefield. I think the answer is obvious. Who is more likely to survive, the generalist. Now, the obvious rebuttal is that the team operates as a cohesive unit. While this is true it does not account for sub-optimal resources or offer the flexibility that is required when in a startup.
In startups, it is suggested that you start your team with generalists and as you scale your team you begin to hire specialists. While I agree for the most with this premise, I would ask the question on what you risk by hiring specialists and how can you continue to extract value from the generalists you originally hired.
You want to be mindful of how you structure information flow so that generalists have the required information to continue to contribute in meaningful ways. For example, let’s say you break your marketing team down by channel. Your head of marketing is going to be the one in charge of finding and then hiring a specialist in new channels. Due to the organizational structure generalists do not have a nice place to fit. If the information flow is focused top down the generalist looses the ability to interject and experiment at potential inflection points.
The other thing to consider with keeping generalists long term is how you are going weigh experience. When you start bringing in specialists that have more experience the generalists may feel threatened. The reaction can be mitigated by how you as a manager approach their knowledge. If you continually express the superiority of the specialists knowledge and compare it to the generalists this feeling of value quickly sets in and hierarchy is formed. However, if you express the unique value specialization brings to the startup as well as the value that having a wide scope of experience brings you level the playing field.