Agile works if done properly. The problem is, most businesses don't know how to do it properly and end up with a bad mix of agile waterfall, which doesn't work at all and ends up with spaghetti code messes.

Proper agile takes time for writing proper unit tests and following a test-driven paradigm. That test-driven paradigm then leads to "fearless refactoring". Proper agile will then take the time to refractor the code to be better.

I was in a company that did proper agile for a while. Problem was, that company was a contractor company and didn't have enough clients so many got laid off. The clients it did have was happy, but they hired more than they could afford to pay from the clients they did have.

I've been to 4 companies since then and not a single one did proper agile. Always some bad mix of agile and waterfall.