Opt-out telemetry in companies based on open source projects has become a critical component of YC applications, VC pitches, and acquisition pitches. If it was opt-in of course nobody would turn it on. It's shady but I also somewhat understand the founders who are doing product-led growth by giving out the product on GitHub/PyPI, yet still need some usage metrics to quantify the stickiness to their backers. Pip installs and git clones/forks are only a loose indicator of real usage.
if it's a paid product and it's part of an agreement for support then sure, but for a free product? when you know some high percentage of users are never going to even know that the option to opt out exists?