From the stress on the system perspective you are right, hard vacuum is not significantly more stressful on the container than low vacuum. But I think the paren

From the stress on the system perspective you are right, hard vacuum is not significantly more stressful on the container than low vacuum. But I think the parent was talking about the cost of maintenance. If the pressure vessel needs recertification over it’s lifetime that will be expensive. If refilling the container requires high purity (and therefore more work removing the air and other contaminants before filling) the process will be even more expensive.