No, it's not obvious. If you don't have any idea how it works, it's easy to read in that statement that not including telemetry in the browser prevents all tracking, including by sites.
This seems more like people having different ideas of what the word 'telemetry' means than a malicious statement meant to mislead users. Telemetry metrics were used before the digital age in diving equipment, rockets, airplanes, factory equipment, etc. Traditionally, they are used exclusively to better understand and improve the performance of the device collecting them (and nothing else).
Recent unethical practices of either using true telemetry metrics for advertising purposes or collecting data not used to improve the software under the guise of 'telemetry' have muddied the meaning of the term. I agree that the author could change the phrasing in that blurb to use a different word which has not shifted meanings in the last decade.
No, it's not obvious. If you don't have any idea how it works, it's easy to read in that statement that not including telemetry in the browser prevents all tracking, including by sites.