I've worked on a system where almost all of the business logic was handled as stored procedures (apart from things that belonged at the UI level, of course). Worked fine, was easy to debug , and performed great. Sure, you had to know how to actually write good SQL, which threw off kids who think programming equals using JavaScript framework du jour, but I don't see it as a shortcoming. No XML anywhere either.

At some point they rewrote it as a web app with NHibernate and all that. Took them literally many hundreds of man-years, and it still runs like molasses. And profiling whatever crap NHibernate emits is rather joyless enterprise.