Allow me to help stir discussion here.
First, here is a link to a thread where someone was claiming that Impale was amazing, but then I explained to him quite exactly why it is not amazing and why Jab is always better:
Javazon is strongest in game - General Discussion - Diablo 2 Resurrected Forums (blizzard.com) post #10
^ This is a very mathematical explanation to your original OP post here.
If they want Impale to be useful, they seriously need to increase its attack speed to standard attack speed and maybe give it a drawback like “defense goes to 0 during animation” or something like that. But as it is now, it’s just not useful at all next to Jab for all of the reasons I had explained in that link.
For a further much more elaborate review of my PRT feedback, just in case any devs are paying attention, it can be found in this thread in post #106: