It's seems like a little thing, but when Go, by design, specified the way the code should be formatted, it highlighted how a small DevEx improvement could have massive impact.
DevEx is all the things that make development better, easier, and ultimately faster.
Code formatting often becomes a religious debate. That's obviously bad, but worse is having different people use different formatting.
Different formatting makes it a little more difficult when reading code, which slows down understanding.
It becomes a huge issue when committing code and reviewing the diffs. For example if someone changes from tabs to spaces, the whole file is different and it's really hard to see the actual changes.