Containers are useful, but it's like having a few similar terminal windows open. Eventually you'll type something on the wrong window... at least I found myself searching for personal stuff on my work Google container.

With profiles I can have different bookmarks, extensions, and even a different theme so I'm aware I'm on my personal profile, not on a work profile. Since switching profiles on Firefox + macOS is a pain in the butt, I use 2 different Firefox channels (stable + dev).

Anyway, containers are nice, but they're not a replacement for profiles.