I think this is an overstatement. If I say "the mass of an electron is X and this is how I did the experiment to determine X", you can repeat all the steps of the same experiment without looking at my original lab notebook.
The more dubious situation is when I say "based on my analysis of a massive quantity of data, which took my grad students a whole summer of full-time work to collect and which I won't publish here, I observe the following pattern which is evidence in favor of theory Y". But even in this case, a competing scientist with his or her own graduate students can collect data from different sources, or a different kind of data, and publish a paper saying "hey, the pattern in this other data provides evidence against theory Y".
The more dubious situation is when I say "based on my analysis of a massive quantity of data, which took my grad students a whole summer of full-time work to collect and which I won't publish here, I observe the following pattern which is evidence in favor of theory Y". But even in this case, a competing scientist with his or her own graduate students can collect data from different sources, or a different kind of data, and publish a paper saying "hey, the pattern in this other data provides evidence against theory Y".