The first question you will likely ask is what is Business Architecture, and to start I will use the definition used by the Business Architecture Working Group:
“A blueprint of the enterprise that provides a common understanding of the organization and is used to align strategic objectives and tactical demands.”  . Now if you read the rest of the Wikipedia article you might feel a bit overwhelmed and being an eager business founder you might say “That’s all great now show me the money, because I can’t see how the overhead of business architecture is going to improve my bottom line in the first 6 months of operation, plus we’re using lean startup so why do we need Business Architecture?” These questions are all quite valid and this is how I see business architecture actually helping your efforts.
Business Architecture is critical in the early stages of a business because it gives you the necessary map and levers by which you can pivot your business as you begin to engage with your customers. Business Architecture helps you to identify the operational needs of your business, and link them to your financial, technology and management needs. It also helps you to identify the key environmental factors that you need to keep in mind especially as your proposition changes in response to the market. It is a well-known rule of thumb that the original concept of most startups seldom survives intact as the business grows. Therefore it makes sense to have a solid blueprint of the business to deal with this change effectively, but most importantly economically.
Now at this point you might say, “That’s all well and good, but my team and I are using Lean startup already so why do we need business architecture?” The response to this is simply lean startup helps you to get your business up and running from an implementation and product point of view, what it does not help you with is actually determining what the product/service is, how best to source nor the best method of distributing it, the two most important factors for any business. The way to look at it is like this, I have an idea to provide a set of widgets or a great service to my customers, however first I need to understand the market, identify my initial customer, look at my initial operating capabilities e.g. I may need to provide customer support via a call center etc., as well as look at how my funding will flow and at what point given the market I am likely to reach profitability. This is all before I even start looking at how I am going to start up lean!! The key thing to realize is that any of the factors above can change my concept quite radically, and when I eventually get my initial customer feedback that can change my ideas even more. This can result in me being in a totally different place from where I started, a place mind you that I might have considered and dismissed at the outset of my idea. Without a Business Architecture Blue Print it is difficult if not impossible (usually from a time perspective) for me to refactor my idea by looking at where my thinking started and where my thinking has ended. The importance of this activity being that I may be skirting the elephant in the room and without the two blueprints I may miss it entirely only for it to be identified and subsequently exploited to my detriment by the competition.
In summary the reason why as a startup you need Business Architecture is because it helps you to stay in control of your business and allows you to grow your business faster using all the modern tools of technology, best shoring and so forth more effectively. It is true many successful businesses have launched and gone on to conquer the world without explicitly using the discipline of Business Architecture, just like many tech companies have launched and succeeded initially without the explicit use of Enterprise Architecture, however for the most part that was yester year. As the world gets more complicated, information and value flows become more sophisticated with markets more competitive, leaving the toolkit of Business Architecture in the box is something the modern Start-up can ill afford.