Right. Regardless of any supposed benefits that keeping your code in a single file might have--or staying away from classes (in C++)--all will be swamped by the substantial decrease in productivity. What is it, specifically, that you are trying to achieve by making things "simple" in these ways? We might be better able to help if you ask directly how to achieve your goal, rather than asking for us to comment on your own suppositions on how you might get there.

If you use all of the tools that C++ offers you judiciously, then the end-result is almost certainly safer, more-robust, and faster than alternatives you would implement yourself, or work-around without. If you are concerned about clarity of codebase, organizing concepts into distinct files tends to be a benefit; if you are concerned about run-time performance, effective use of custom objects and of the standard library yields fast code--there are times you may need to step away to gain that last 10-20% of performance, but you shouldn't step away from the beginning if practical matters concern you. In short, I can't think that this would be a particularly fruitful endeavor.