[gomaaa]

Read the next sentance. The same chemicals that would protect a cell by absorbing UV light could easily be used to provide energy for the cell. These chemicals are nothing particularly special. We have specialized pigments in our eyes for seeing, but similar chemicals give our skin color and power photosynthesis in plants.

[AndrewC]

Read the next sentance.

Read the prior logic, you are the one saying protection. That means it breaks something important that preexists(unless a cell thinks). That makes it a problem.