Why did Richard Feynman appear to recommend replication before manipulation when conducting lab experiments?
I think it's a basic concept of experimental design that you have control groups. So for example, if you want to study the effect of X (e.g., a drug) on Y (e.g., performance), you could manipulate X (e.g., give half the drug and the other half no drug) and randomly assign the participants to either group.
Random assignment is a strategy for making the groups on average equivalent. Thus, it is an attempt to control for confounding factors that might cause Y.

Of course, you could say that other researchers have conducted the equivalent of the control group condition, and just do a one sample study with just the drug condition. However, studies differ in all sorts of ways (participants differ, your exact measures might differ, the context might differ, etc.). Thus, you couldn't unambiguously attribute any changes to the effect of the drug.

That said, we often do compare the experimental outcome of different studies that differ in some respect. For example, meta-analyses often examine moderators which compare effect sizes across study features. While this is useful, you'll often get a cleaner answer to your research question by incorporating the moderator into a specific study where there are fewer alternative sources of explanation.