So what can you do? Real life is too short to demand proof of everything all the time. If it's not life or death, you take what you've heard or read for what it's worth, at the risk of being misinformed.
Research starts with the literature survey. You collect everything that's already been said and done that looks relevant. You figure out where it came from and what its limitations and weaknesses are. Questionable work may need to be redone, but you aren't going to redo everything from scratch.
You get up to speed with the literature before you go looking for new primary data, otherwise you're very likely to misinterpret what you find.
On WikiTree, ideally, this would be a collaborative process. Somebody starts a profile, and everybody uses it as a chalkboard to collect links to everything that's out there.
But the stupid new "reliable source" rule says you can't do that. Now, unless the reliable research has already been done for you, and you only have to copy it from Great Migration, you have to do your literature survey offsite and get into the original research in hard-to-access primary sources before you can even create the profile. Where's the collaboration?