If engineers want the business to pay them for simplifying maintenance, they can identify a collection of support tickets that have a compelling root cause, and propose refactoring that system to eliminate the bugs and maintenance issues.
What I usually see is us engineers calling it “tech debt” and complaining we never take time for it, which is about as effective as the bookkeeper complaining about the paperwork that debt payments create for him. Businesses love debt. It’s a useful financial tool. The business doesn’t get the issue.
We also increased profit by lowering our runtime cost by some of those optimizations.
A large part of my career has been telling my boss "we should invest 5h of cleanup time here to make sure that in the future we won't have those 5h worth of obstacles here before building a new feature on top of it".
In industries where requirements change on a weekly or monthly basis, agility is worth a lot.
So, indirectly, yes: you can get promoted and collect revenue by simplifying and refactoring.