I have not held an oblique holder.
I have not written with a straight holder.
I have not even an india ink to dip.
So I can't comment on this subject.
I do believe when one have a tool, be it a crayon, a pencil, a pen, or a brush,
One can accomplish the same task as another if one knows how to use it fully to its full function.
However, the production might not be exemplary.
As Andy have pointed out that these scripts were before the steel pen. There is no rule on which tool to use for which script.
It is a matter of preference, and the ability of the user for that tool.
To me, a straight holder is more versatile, as you can change grip position and flourish. While an oblique use have to turn the paper.
In the end, it is your fluency and comfort in using a tool dictates your production quality.
As for Pascal, he has long fingers, you can see he uses both finger moments and some arm movements.
I have short stubby fingers, so, I can't do finger moments and achieve the same results....
As Master Penman Joseph Vitolo said .... even JC Ryan, the Handless Penman can do it, so can you.
And I'll bet JC Ryan didn't use an oblique holder.