That’s the difference between truly new approaches to modelling an existing problem, or coming up with a new problem. No set of a bit different results or missing exact hyperparameter settings really invalidates the value of the aforementioned research. If the math works, and is a nice new point of view, its good. It may not even help anyone with practical applications right now, but may inspire ideas further down the line that do make the work practicable, too.

In contrast, if the main value of a paper is a claim that they increase performance/accuracy in some task by x%, then its value can be completely dependent on whether it actually is reproduceable.

Sounds like you are complaining about the latter type of work?