Leadership principles (LPs) are not contradictory so much as they are in tension with one another. That's not a bad thing, it's a good thing. Navigating the tension is what helps discover good outcomes. For example, if a customer calls up wanting a refund, then granting the refund supports Customer Obsession but contradicts Frugality. When deciding between options, there is always a tradeoff, and the LPs provide a lexicon for identifying and reasoning about what you're trading off. Amazon strives to be the world's most customer-centric company, and hence will generally choose the approach consistent with customer obsession.
Identifying and discussing that tension and how to resolve it is constructive.
I don't see them as arrows to knock people down. I see them rather as, well, principles to use when reasoning about a situation. Giving a name to a concept is a good way to reason about it and discuss it. They are used when reasoning about performance, it's true, but it's used across the board: when justifying a promotion, when praising a high-performer who excels within their level, when identifying areas of growth, as well as while discussing job performance with people who are doing less well.
Performance and leadership in a creative job like software engineering cannot be perfectly objective (it's not like an assembly line where you process N units per hour), but the LPs provide some objective concepts and terminology to apply while discussing performance; they break down performance into dimensions that can be discussed individually in the context of examples, which is an advantage over just vaguely discussing things at a high level. For example, "Bob found a creative way to pack more software onto existing servers without harming performance (Frugality)" or "Sally spent two hours on the phone helping our biggest customer (Customer Obsession)" or "After causing an outage, Joe wasn't able to identify anything he'd do differently next time. I'm concerned that he's not vocally self-critical." I'd much rather have a discussion of my performance or leadership in concrete terms like these, rather than vague ones.