This sounds like standard title inflation, and it's not restricted to just technical ladders. It's certainly a problem, but I don't think we should discount the idea of principal engineering roles just because job titles can be misused or abused.
The company I'm at has a single principal engineer. He was hired externally. Within a year of starting, he'd had a bigger impact across teams than the CTO in the same time period. He doesn't necessarily write tons of code, but he's also not sitting in an ivory tower telling other developers what to do. Rather, he very quickly got in tune with the sorts of technical problems being faced by basically every team and developer at the company and started introducing various techniques and technologies to resolve pain points around the organization. Before long, we were doing things that wouldn't have even been possible before.
Few places are hitting 12 on the Joel Test twenty years on. That, unit/integration tests, and a "message bus" with metrics dashboards and you're above average.
The company I'm at has a single principal engineer. He was hired externally. Within a year of starting, he'd had a bigger impact across teams than the CTO in the same time period. He doesn't necessarily write tons of code, but he's also not sitting in an ivory tower telling other developers what to do. Rather, he very quickly got in tune with the sorts of technical problems being faced by basically every team and developer at the company and started introducing various techniques and technologies to resolve pain points around the organization. Before long, we were doing things that wouldn't have even been possible before.