If the individual can't survive outside the swarm they will become more similar to others in the swarm.

Any individual member of the swarm will increasingly look like any other.

Consider two red blood cells; they're practically identical.

Once you submit to the swarm and its logic, the power of the collective, the individual has a crutch: they no longer need to be viable as an individual.

That allows them to exist more cheaply, to shed lots of complex machinery and effort, but it also means that they can no longer exist outside the swarm.

Ants become extremely similar because they aren't viable outside of the swarm.

The swarm would prefer the individuals to be replaceable, the same, cogs in the machine, because then it can handle them with more efficiency.