I'm curious what you mean by being a fabrication? Their ideas were real and they've shaped history throughout time one way or another
I don't think it makes the content itself any worse, but it's difficult to know what was really historical.
I don't formally study this, but such problems become quite apparent when I try to e.g. find out historical sources for some philosophical statements or anecdotes. Probably not that different from how people attribute all sorts of "smart stuff" to Einstein.
https://en.m.wikipedia.org/wiki/Pseudepigrapha
Edit: by "scholastic fabrication" I mean that scholastics spent a lot of time "interpreting" especially Aristotle (and tried to make it compatible with the Bible). I'm guessing a lot of what we think is "greek philosophy" may be from these interpretations.
History is god damn hard. That's why it's useful to read the source material whenever possible.
I don't know how many times I've seen The Parable Of the Cave being used, but reading The Republic, really makes you understand what Plato meant with that story.
It's hard for most people to read that stuff though. I've only scratches the surface. It's easier to trust others to donor for us and distill the information.
And in each century, the lessons learned from the same material may be different too.
For most things it probably doesn't matter that much. For example classical philosophy (or its common translations/interpretations) provides a sort of "shared language" for academia, regardless of how historical it is. That's why I tend to think it more as a myth unless there's something specifically historically intetesting.
Most of the classical stories, e.g. the Cave, have "transcended" the original context anyway, and are in a sense richer nowadays.