Yes, you get an analysis of the problem, which is *not* the "any result you want" you implied.
If I model a calculation of the square root process, and I use it to get a result showing that the square root of three is 1.7320508, is that only because I *want* it to be that, or because it *is* that? Can I "make" the square root of three to be "any result I want"? No, I can not.
Computer models are used to analyze processes and tell the people using them what happens under certain circumstances, not so that *they* can tell" the model what happens.
If that's how *you* model things, you've been doing it all wrong.
I repeat, you're grossly misrepresenting the nature and use of computer modeling.
I've been a programmer for thirty-two years. How about you?