Simple question perhaps, but one I'm having a hard time finding the answer to. I often work at a client that uses TFS as source control and they completely avoid using the baseless merge feature of TFS source control
In part because in the past it required a command line tool to do it, but possibly more important because when you do it now in the interface it shows you a yellow exclamation warning symbol that you are indeed performing a baseless merge.
This sort of scares them off and makes them avoid it altogether. I've been searching around to figure out if there are any specific risks involved in baseless merges but I'm unable to find that out (or details on how baseless merges work underneath the hood)
Baseless merges should be avoided if at all possible. When you do a baseless merge, unlike a merge, you are disregarding the history of either side. Indeed you can merge two branches that are totally unrelated—and that can be dangerous.
The key is to create a branching strategy that allows you to not have to use that feature.