I've been using the Containers plugin and its predecessors for years to isolate facebook, but I've always liked it because when someone links to facebook content I can then read it logged out in my normal tab. Obviously on top of this I am using ublock/umatrix anyway.
It would be counter intuitive if this is how the standard Containers extension worked, but for this specific extension, you are installing it to isolate Facebook, so I think this is how people would expect it to work. If the extension did not open Facebook links in a dedicated Facebook container, then I think the extension would not be doing its job correctly.
To automatically open Facebook links in a logged-in, dedicated-to-FB container is the entire point of this extension. After all, it was built for regular, non-tech-savvy people. To such people, it'd be a bad experience if suddenly they could no longer open FB links sent to them by their friends (because links to FB posts can have non-public visibility).
Personally I've trained the habit of opening most random links in private browsing mode. Besides achieving what you mention it seems like good, additional mitigation against tracking/security/etc. The only downside is lack of browsing history but I've never had much use for browsing history (mostly because I've found the search functionality in browsers to be useless).
I think your observation is a good one, and a rule for it should be added (or actually the third rule should be modified).
Firefox Multi-Account Containers is an extension [0] that allows you to compartmentalise cookies and other data into different containers. It's possibly best explained by thinking about how you might use it:
Suppose you have two Twitter accounts: a personal account and a business account. Twitter usually only allows you to be logged into a single account at a time. This means that if you're currently logged into your personal account, you need to log out first before you can use your business account.
With Containers, you can simply create a Business container and log into your business Twitter account in there. That way, you can be logged into two Twitter accounts at the same time.
Containers do not act as ad blockers and perform a very different function.
For more information on Containers, I would suggest reading the extension's description [0] and/or the support page [1].
This article is talking about a special version of Firefox Multi-Account Containers called Facebook Container [2]. This works similarly to Firefox Multi-Account Containers, but it isolates Facebook to its own dedicated container.
[0] https://addons.mozilla.org/firefox/addon/multi-account-conta...
Firefox Containers don't block ads, trackers, or anything. Instead, they isolate websites into their own "containers". Think of it like private browsing mode. Except each container is its own, separate private browser, and they persist.
They're different approaches with pros and cons, but they can certainly be used together since they're orthogonal.
Personally I use both. uBlock blocks ads/trackers/etc for me, while I use Containers as additional protection for not just social media sites but also to isolate my banking activity, work accounts, etc. It's useful for when you have multiple logins to the same site, and for mitigating some attacks (e.g. CSRF). [NOTE: I'm using the full featured Multi-Accounts Containers add-on, not the Facebook Container add-on mentioned in the article]
That's what they advertise, but it's not even remotly true. I've made a bit of an exercice to see how they are working. Basically they all (adblocker and tracker removal) have a database of bad guys and avoid the known bad guys to load. The problem is all the unknown bad guy. We would need something that is behavior based, not database based, doing my research I couldn't find one that was working as one would expect.
Just as 1 example of the bad guys: Cloudflare that send cookies when the owner of the site is using their CDN regardless if you have setup a do not track header. Do any of those track blocker managed to block Cloudflare? Nope
It makes me sad that our community for some reason I ignore don't even respect the do not track header. It literally is just decoration
https://www.eff.org/privacybadger
The basic rule is that if more than one first-party site tries to connect to the same third-party, that third-party could be tracking you and will be blocked. But it's a little cleverer than that, and has etra rules to just block cookies from common CDNs.
False. I just visited cloudflare.com and uMatrix blocked 2 Cloudflare cookies, 8 Cloudflare scripts, one tracking pixel each from Bing and Google Ads (who are on the "bad guys" list), a script from Optimizely and an embedded frame from Google Tag Manager. That's with a whitelist that only allows CSS and images (the default, I think), and only from first-party sources.
Surprisingly, the site wasn't even broken.