Containers are the killer feature of Firefox over Chrome and the reason I recommend it to family and friends. In my opinion they're not a power user feature at all, everyone and anyone can get instant obvious benefit from them. Multiple logins on the same service, controlling how you are tracked, just to name a couple.

Attention and effort are expensive and 'install and just use' gets you a material percentage more users than 'install and then click through this menu system and install something else'. Containers should absolutely work out the box.