Do the simplest thing that could possibly work

Generally speaking, when I hear people say this, it's a huge red flag. Really, any time anyone puts forth any kind of broad proclamation about how software development should be done, my hackles go up. Either they don't know what they're talking about, they're full of shit, or both. The only reasonable thing to conclude after lots of experience with software development is that it's hard and requires care and deliberation. There is no one-size-fits-all advice. What I want to see is people who are open-minded and thoughtful.

Simplicity (meaning the inverse of complexity) is usually the most important factor when considering two possible ways of doing something with software. And this is because it has to be conceived of, pitched to, agreed upon, built, and maintained by humans.

Unfortunately, simplicity is complicated. The median engineer in industry is not a reliable judge of which of two designs is less complex.

Further, "simplicity" as an argument has become something people can parrot. So now it's a knee-jerk fallback when a coworker challenges them about the approach they are taking. They quickly say "This is simpler" in response to a much longer, more sincere, and more correct argument. Ideally the team leader would help suss out what's going on, but increasingly the team lead is a less than competent manager, and simplicity is too complicated a topic for them to give a reliable signal. They prefer not to ruffle feathers and let whoever is doing the work make the call; the team bears the complexity.