No, they just aren't affected by the old bugs. Most bugs affect only a small fraction of users, because bugs that affect many people are usually found during QA

No, they just aren't affected by the old bugs. Most bugs affect only a small fraction of users, because bugs that affect many people are usually found during QA. So the majority of your users will not be affected by the existing bugs. If a customer doesn't change their workflow, they aren't going to suddenly stumble over an old bug. But if you keep pushing changes, eventually you'll introduce a new bug that does affect them. There's no way around it: The more you change software, the higher the risk of introducing bugs. That applies even if the changes are just bug fixes for old bugs. Every time you fix a bug that I wasn't affected by, you risk breaking something that I do use.