In almost 50 years of using live rubber and now silicone skirts, I've never had one tie its self into knots. I've never even head of anyone make that complaint. I don't even know how one would. But I guess I've been lucky all this time.
Here is a pic of a silicone skirt on a wigglewart and vinyl skirts on some homemade lures for comparison. I think one can draw their own reasonable conclusion as to which one is more tangle free.
There is some truth that skirts can affect the motion of a bait. But that has more to do with the size of the skirt than it does the material. And it will also depend on the type of bait it is used on.
Obviously, the wigglewart has a much broader wiggle pattern and the effects of the skirt, if any, are minimized. But a skirt of that bulk could cause problems for a lesser bait.
And all skirts are not created equally even from the same material. Manufacturing standards are different. If you're complaining about the collars being to thick or to thin or what have you, it's probably the choice of manufacturer not the choice of material that is your trouble.