What does "high observability maturity" ultimately mean — and what is the common misreading?

It means using the right data effectively, not collecting more of it; the misreading is to equate maturity with volume of telemetry.

The journey the phrase describes: from monitoring to transparency, from reactive operation to understanding, from searching for faults to proactive action and automation.

The misreading is seductive because volume is easy to measure and easy to buy. Adding another exporter, raising the sampling rate or keeping logs for a year all feel like progress, and each one produces a bigger bill, a slower search and more noise between you and the answer. Recall Ranum's first law: data nobody will ever look at is a cost, not an asset.

What high maturity actually looks like is narrower and harder: the right data, correlated well enough to answer questions that were not anticipated, used to run systems that are reliable, performant and oriented to the customer. It is a practice, and like any practice it is never finished — which is why the honest description is a journey rather than a target state.