It's slow at the beginning, but the payoffs are huge. With mobbing, everyone knows how to do everything. Far less design mistakes are made. No one ends up "owning" certain parts of the system. It's also very humbling as everyone succeeds and fails together, discouraging "heroics". Pairing is also great for this (but you have to switch every day).

Obviously, if you're working in a feature factory, pairing and mobbing are pointless. If you care about code quality and de-siloing, they're incredibly valuable.

Obviously, it's not for everyone, but it works incredibly well where I work and I will never accept another job that doesn't encourage pairing by default.