The rationale is if you make a specific population you don’t like extremely likely to get felonies due to scenarios you place them in you can prevent millions of people from voting. It’s one of many ways the US creates second class citizens and cheap (basically free) labor. Wildfires in California are fought by people in prison, products are made by them too.
The US loves cheap/free (slave) labor and removing the chance to vote and change these unjust laws benefits the oppressors much like preventing enslaved people from learning to read