The main problem is that many developers will increase technical debt when they try to fix it. For example, some will try to fix technical debt by writing a new

The main problem is that many developers will increase technical debt when they try to fix it. For example, some will try to fix technical debt by writing a new framework. Then the new framework doesn't handle all edge cases, so you still need the old solution. Now you have two different conflicting styles creating more technical debt. The next developer will come in, see the mess, and promptly start working on a framework to consolidate everything... So whenever you consider fixing technical debt, ask yourself if the team is skilled enough to actually create a cleaner solution. If they can't then it is just a waste of time. The best predictor of this is that they have created a cleaner solution elsewhere, if they haven't then don't let them work on technical debt unless they have an extremely well thought out plan.