I would guess that a lot of the validation for studies like this comes from marketing research. Marketing often does "study groups" to try to figure out if, say, one product name is better than another. Would you buy "ZimZam Fluid" or "Superlicious"? The study participants are not confronted with the actual product (it may not exist yet) but have to imagine which they prefer. If this approach shows success in marketing (which is all about peoples behavior) then it seems likely it is useful for figuring out other things about how people work and what they will think in specific situations. What people imagine is a clue to how they think, you could think of it as a simulation. People often imagine future outcomes as a way to make decisions in the real world.
What you are also saying is that the way research is funded determines how research is done. You need a reputation to get big money. To get a reputation you have to start small with the little money/time you have. Hence lots of studies are done that are too small, not well controlled, and are essentially useless because no one will believe they have conclusively proved anything. However, once you get 10 papers based on these poor studies you start to look like an expert and it becomes easier to attract bigger grants. By this time you may have actually formed some ideas about what it is you want to research as well and abandon your original ideas as castings in the dark. So it's good in that it helps focus research and helps researchers gain experience, but it is bad in that it results in lots of studies that are not very useful to anyone (like all the medical studies you read about where, when the topic becomes important like in a pandemic, you will find scientists calling out studies as underpowered, too small, not an RCT, and useless.)
It seems possible that making the basis of getting a PhD be making a unique discovery ("your contribution" as it is called) is misguided. It results in the above useless studies to gain reputation, plus it means researchers won't touch each others ideas for fear of being labeled derivative instead of unique. It may be much better to have all scientists in a field brainstorm ideas and contribute them to a common list and then individual grad students and researchers could choose one. The list could be ranked by the same crowd (and hopefully by outsiders as well) and used to assign grant amounts ahead of the selection of an actual researcher applying for the grant. That might result in better and more important topics being studied, an easier path to reputation for new scientists, and more useful studies being done that will actually advance science. Or maybe it would mean that a cabal of scientists and politicians take over the list and misdirect research for decades, which would not be much different from what we have now.
What you are also saying is that the way research is funded determines how research is done. You need a reputation to get big money. To get a reputation you have to start small with the little money/time you have. Hence lots of studies are done that are too small, not well controlled, and are essentially useless because no one will believe they have conclusively proved anything. However, once you get 10 papers based on these poor studies you start to look like an expert and it becomes easier to attract bigger grants. By this time you may have actually formed some ideas about what it is you want to research as well and abandon your original ideas as castings in the dark. So it's good in that it helps focus research and helps researchers gain experience, but it is bad in that it results in lots of studies that are not very useful to anyone (like all the medical studies you read about where, when the topic becomes important like in a pandemic, you will find scientists calling out studies as underpowered, too small, not an RCT, and useless.)
It seems possible that making the basis of getting a PhD be making a unique discovery ("your contribution" as it is called) is misguided. It results in the above useless studies to gain reputation, plus it means researchers won't touch each others ideas for fear of being labeled derivative instead of unique. It may be much better to have all scientists in a field brainstorm ideas and contribute them to a common list and then individual grad students and researchers could choose one. The list could be ranked by the same crowd (and hopefully by outsiders as well) and used to assign grant amounts ahead of the selection of an actual researcher applying for the grant. That might result in better and more important topics being studied, an easier path to reputation for new scientists, and more useful studies being done that will actually advance science. Or maybe it would mean that a cabal of scientists and politicians take over the list and misdirect research for decades, which would not be much different from what we have now.