It doesn't block everything, but almost nothing is getting through for me.
Back in the late 1990s I used to have all sorts of software in my computer which I downloaded and installed. Some of it was purchased and other free or open source.
As the time passed, more and more services became "web based" including mail, music, calendar, note taking, etc.
I was part of a small group that did not like that. My reasoning was that there was no need to hack all that functionality in the web browser as it was highly inefficient. That it was better to code the network features into the desktop clients.
Web caught on and nowadays seldomly you get a client program in the desktop.
But now in mobile, we are returning to the clinet software first approach. And for some reason we resist the installation of client software and prefer browser based functionality.
IMO for any given program or 'app' today, the better it functions offline directly correlates with the desire I have to use it natively on a given platform, as opposed to web access.
Slack is just about useless offline, hence my strong preference to use it in the browser.
You can reverse each of those statements for a current mobile app.
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[0] - http://jacek.zlydach.pl/blog/2019-07-31-ads-as-cancer.html