It's not insane. The best codebase I ever inherited was about 50kloc of C# that ran pretty much everything in the entire company. One web server and one DB server easily handled the ~1000 requests/minute. And the code was way more maintainable than any other nontrivial app I've worked on professionally.
I work(ed) on something similar in Java. And it still works quite well. But last few years are increasingly about getting berated by management on why things are not modern Kubernetes/ micro services based by now.
