Telemetry is far more than stack traces. It includes domain names of visited websites, names of executable files you've run, names of documents you've opened via explorer, clipboard contents, keyboard logs and other privacy-sensitive data.
And switching between Basic and Full levels of telemetry in settings doesn't help too much. According to BSI (project SiSyPHuS), number of event providers for Basic telemetry level is 410, and for Full level there are 422 ETW providers.
Specifically, it has the option to enable a "Diagnostic Data Viewer" that shows the data it sends (as JSON). I've just enabled that, so there is not much to see, but so far it has only transmitted version information of OS software components.
(Mini-) crash dumps can contain all kinds of information but that is kind of unavoidable. As a developer, I'm gratefull whenever I get a core/crash dump, but yes, it shouldn't be automatic.
Windows 10, when left alone for 1 year, sends about 4.5 Gb of outgoing data. There are no apps running all this time, so there are no crash reports to submit.
And switching between Basic and Full levels of telemetry in settings doesn't help too much. According to BSI (project SiSyPHuS), number of event providers for Basic telemetry level is 410, and for Full level there are 422 ETW providers.