I wrote up a quick email to friends/family at the beginning of the pandemic about Firefox containers in regards to the vaccine signups that were occurring. Since there was site isolation you could get as many “slots” as you were willing to solve capchas. Most of my friends and family were vaccinated because of this feature. A bunch say they use it now a days for normal site isolation but I did at least convert some people off chrome that way.
You would think but no. Open a private window and log into a site. Then open another and it’ll be logged in. Incognito windows share cookies. They are deleted once incognito mode is turned off but that doesn’t help us in our “open 100 windows at the same time to get a bunch of slots” use case here.