> Are you claiming programming or software systems cannot be a subject of scientific process?
I'm saying it's extremely difficult and expensive to answer most of the questions that you want to know through scientific experiment. Usually the best you can do is experience.
That's not a bold thing to say. There are plenty of areas that are really hard to study through experiments, but we can still learn things through experience. The whole field of psychology is just on the edge of being amenable to experiment, but it's not like we know nothing about human psychology.
Management is another field where it's more or less impossible to do scientific experiments to determine what makes the best manager, but again that doesn't mean we know nothing about management.
Very occasionally there are great scientific studies of software - e.g. that paper where they found that Typescript/Flow prevent ~15% of bugs in Javascript software. But most are along the lines of "we took some undergrads, gave them a tiny task, and measured how long it took them" which has no correlation with best practices for professional long-term projects - maybe even negative correlation. For example I suspect it would tell you that adding any comments to code is a bad idea!
> Talking about "technical debt" of software system is no more useful than talking about its scent.
Why do you think talking about its scent is not useful?