It was easy to throw hardware at a sequential problem, a decade ago. CPUs were still improving their single-core performance year after year, and memory access and all kinds of IO devices kept getting faster and better. I'm guessing that time was where this idea originates from.

Today, things are different. Single-threaded performance isn't going to be improving much in foreseeable future; the effort shifted to improving parallel performance and, more recently, power consumption. So if you write slow code - perhaps by choosing a slow software stack - your code will remain slow.

It is also a bit less easy to throw hardware at a problem when your software is actually embedded firmware. Upgrading or adding hardware reduces your profit per unit.

But TBH in this particular field Moore's law still rules. Sometimes you are forced to upgrade to a better component for the same price because the component you chose five years ago has reached end-of-life.

Yet paying attention about optimization allows you to do more with what you have, or sometimes allows you to use less optimal but more convenient or simpler approaches.