Design systems are definitely the thing now, but they're often equated with having large design and development teams that needed ways to scale design while keeping everything consistent. My professional experience is mostly with smaller product teams, like Lifetramp, anynines or Lilt, and it shows me that small teams can benefit from having a design system from the beginning too. Here's a couple of reasons why.
We all know about Lean Startup and that you're supposed to push ideas to your customers as quickly as possible, learn from them and iterate, right? Exactly. While having a design system (or a proper, well thought out UI framework, for that matter) is an initial investment, nothing screams speed of development more than being able to literally connect a bunch of ready-made components that already look like they belong in the interface and push it out to testing. The end-game of rapid prototyping is being able to develop production-looking tests and prototypes, and having a design system allows you to do just that.
So you've hit the spot, you're getting millions of dollars in funding and now you're looking to expand your design team from one, overworked designer to an actual team? You're actually still trying to figure out the scalable business model but you have to hire some freelancers to help, so you can focus on important stuff? Perfect. Having a design system lets you quickly onboard new people into your product team by literally giving them a handbook with a list of design blocks and how to use them and in which context — like IKEA instructions for your product!
Reduced Communication Overhead
With properly documented and well thought-out design system, gone are the days in which developers and designers butt heads around spacing and tiny visual details. Because you have a source of truth that's been agreed upon by both teams, built in a way that makes everyone's life easier (designers don't have to do much QA, developers don't have to remember pixel values for spacing, for example), you have way less bickering and way more productivity. Bonus cookie points if you actually implement components in a way that does separation of concerns between data and visual layers.
Because all the foundations have been agreed upon and built, you can focus on what's important – building the best product for your customers — without getting bogged down by small things. Need a new component? Chances are you can at least partially build it using your smaller components. Need to communicate the layout? Chances are you can just draw it out on paper and signify what goes where, and a developer equipped with his UI framework built on the design system can build it for you. That way, you can focus on getting your product right, without worrying about getting your interface right.
So yeah, here you have it. Style guides, UI frameworks and — by extension — design systems are definitely an up front investment and that's why a lot of smaller companies try to forgo building them in the beginning. Arguably though, a design system is something that removes a lot of friction when done right and, as a brand exercise, could actually help you figure out the underlying values and principles you want your product – and your brand — to represent.
So go ahead, try building one at the very beginning, so when you have to scale, you can scale quickly and effortlessly.