There three classic reasons for the criminal law of sanctions:
- To protect society from further depredations of the convicted;
- To rehabilitate the offender; and
- To deter others from similar rascally behavior.
Point three is the one I think you refer.
While it is true that felons cannot own a gun, there as a UNIVERSE of occupations closed to them. They can't be lawyers, doctors, dentists, nurses, CPAs, professional engineers, and more. They can't own a child-care nursery or a plant nursery, they can't get a commercial driver's license for hauling hazardous chemicals, they can't join the military, they can't own or even work for an exterminating company.
The have a VERY hard time getting bonded, so most occupations handling money are forstalled. Things like bank tellers, retail clerks, or ticket sellers at the movie theatre.
They can't vote or hold political office. They can't be involved, even at the margins, in law enforcement. In some places, they can't even be a notary public!
I've painted with a broad brush on the above. Certainly there exist jurisdictions where some of the above sanctions do not apply, but nowhere are ALL the constraints missing.
It's a bad hat to be a felon.