It's actually more than that. Software design/architecture is always for new never-before tested or built products. Even building a new mobile app is generally

It's actually more than that. Software design/architecture is always for new never-before tested or built products. Even building a new mobile app is generally building something never before seen. When you compare this to an architect designing a bridge, there are thousands of identical water-spans that have had bridges built on them. Most of it is just following best practice. If you want to try and compare architecture for a building to architecture for software, the closest you can get is to designing a building on mars. Sure, you've designed walls before and water proof buildings for ocean use, but you've never built on Mars before. Every single time, for every single novel software project, you're designing something new. This is why software is hard, and why trying to manage or build software as if it were a bridge nearly always ends in tears.