How would that work? They were able to lift up the evil barbs, but weren't able to cancel the whole web of darkness with a reverse weave like Nynaeve did?

That itself may be what differentiates what Nynaeve can do and what they could. Again, the only factor that differs is the presence of the taint.

I'm sure you at least agree that those Aes Sedai who could grant a few moments of lucidity could Delve and find the net of taint-compulsion that Nynaeve did? And since some of them would have been from the same era as Lews Therin, like him they would also know of the way to cancel compulsion?

The the only real difference is in their ability to permanently remove the web. Whether they failed because the presence of the taint prevented the cancellation or because immediately after cancellation, the taint started seeping back makes no difference. Sidious is still right.