Disagree with this article's thesis that the Webextension webrequest API should be removed.
By moving to a declarative blocking API you are limiting the possible ways for extension to function to blocking and redirecting. This is a very narrow use-case, based on the current prevalence of blocking extensions.
But this is not the only way to solve problems such as blocking ads and improve privacy, as shown by privacy badger and Cliqz' tracking protection.
The performance has been shown not to hold for adblocking extensions (https://whotracks.me/blog/adblockers_performance_study.html), and there are many other problematic webextension APIs w.r.t. privacy.
The solution to these issues should be institutional, not technical. Google should impose performance constraints on extensions, and audit what data extensions are sending home. However, looking at the rampant malware on all their stores, this is something they're unlikely to do, so instead they'll nerf extension's capabilities.
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