Is Google Analytics still useful and how accurate are its stats? How much data is missing from Google Analytics due to adblockers and privacy-friendly browsers?

The level of Google Analytics blockage varies by industry, audience, the device used and the individual website. In a previous study, I’ve found that less than 10% of visitors block Google Analytics on foodie and lifestyle sites but more than 25% block it on tech-focused sites.

But how about a very tech-heavy website with a tech-savvy audience of hackers, developers and the like? How many visitors do sites that use Google Analytics miss out on from referral sources such as Hacker News or Reddit?