For many years there were people repeating "%PLACEHOLDER% is not a silver bullet". OOP, FP, MVC, DDD and agile are pretty memorable examples. Why do we stick to non-silver bullets then?

Apparently, because we consider imperfection to be acceptable. Do I need to say it's okay? Now, what I must say though is why it was acceptable, and if anything has changed since then. At big scale it's difficult to maintain flexibility, speed and quality. Basically, it's a constant trade-off that big companies use. To maximize margin, they use all tools designed for observable planning and replaceable cogs. I call it controlled destruction, because even if everything falls apart, house always wins. Many non-silver-bullet solutions are mostly shining here. You don't want or have to use OOP for the task you're given, but if you won't, it will cost uncertainty for the company.
It can't tell how complicated it is to add new features to the initial requirements, nor how long it takes for a newcomer to grasp how it works or deployed. The task could be done with two lines of python code, but company does not have python in their stack. You ought to use java. Java apps in your company are deployed in spring boot environment only. Via terraform and helm charts ofc. And don't forget to write tests for it.
So, can java or terraform be considered silver bullet?
Nope.
Why?
Because we intentionally put it into an absurd situation.
We're, basically, using flamethrower for cooking, and then pointing out that it doesn't work for some(!) dishes. Of course it doesn't - it's not meant for cooking in the first place!
That didn't confuse big companies so far though. I'm not for too long in the industry. Still, I couldn't help but notice how it unfolds a peculiar transition of mentality. Developers are hopelessly swinging from one cargo cult to another, some of them are aware yet unwilling to resist. It naturally leads big tech to overengineering and overspending (overexpense?). Prices go up, tools are shaped to match new odds, useless work piles up, burnouts happen.

Since AI has advanced so far, recently, tides are moving towards indie development. Devs are just more capable of achieving things on their own. It makes all that corporate ballast redundant, allowing them to do what they want to do in a most efficient way they possess. They don't need OOP jungle or k8s with containers nor other stuff to implement discord bots, web pages, browser extensions in plain and simple way. Soon silver will, probably, melt, and flamethrower chefs will be banished with their obsession.