This sounds like the kind of thing that is good for startups, where everyone sits at the same table, including the big boss. But once a large corporate structure sets in, it degenerates.

In spirit, "don't complain, fix things" means you can do things without asking for permission, as in "don't complain if you can fix things instead". If your software crashes because it misses a null check, just add that check and move on. Don't request to have it included in the next sprint, assign it points, have it prioritized by some manager, only to have it assigned to someone else who will then call you back for explanation. Here "don't complain" means something more like "you don't have to write a ticket".

But once the corporate hierarchy comes up, fixing something without telling managers becomes unacceptable, how are they going to meet their KPIs if your work doesn't show up on their dashboards? The saying stays, but it becomes perverted into "don't complain unless you can fix it", which is the complete opposite of the previous idea.