If a person's $100k salary loses 20% of its value, but their $400k in mortgage and student loans also lose 20% of their value, it will be years before the lost value from their salary outweighs their 'gain' from the reduced value of their debt. They'll then have opportunities to increase their income, usually with the help of rising wages that accompany inflation, but that reduction in the value of their debt is permanent.

There's not a lot of scenarios where inflation doesn't push wages up. At some point workers demand and receive an inflationary match.