At huge companies, it's hard to prioritize this because it's hard to pin dollar values to removing legacy code, while it's easier to show how building feature X will earn the company $Y amount of revenue. And because of that, there is also no incentive to do it, you don't get promoted by deleting old code, you get promoted by showing how your effort helped contribute to company revenue. At my previous company (100+ engineers, hundreds of microservices), teams that regularly clean legacy codebase tend to be platform teams (cost centers), while teams that struggle to get these prioritized are product vertical teams (revenue centers).