Again this is you moving goal posts. If she opted to blink into the backline then she evidently won’t have that blink available to escape as she’s consumed it, and in turn pull off the W tether. At that point she’d be stuck committing to her Q. And all of this just show you’ve moved goal posts with regard to your issue, because from that scenario she can’t pull off W+E.
Her teleport also doesn’t remain static so actually following Maiev means you’re reducing the distance between you and Maiev during the teleport. Remember how the mechanic actually works, after the shade reaches maximum distance it starts to journey back to Maiev. Meaning you have counter-play with regard to her distance, travel time, and the telegraph of where it is going at all times; which taken together don’t make the combo as “impossible” as you’re trying to describe.
Or you know you’re not even attempting to understand the different tools to dealing with Maiev because you keep formulating new scenarios that just move away from you initial concern. There is no focus with regard to your thoughts this is why you can’t seem to formulate or grasp the weaknesses of this interaction, or the design behind it. Especially when you completely ignore all the tell-tale signs of the combo which can be seen a mile away… Because literally, there are a lot of visual queues here for players to react… Which is why…
Yes it is not effective very often because there are enough weaknesses to exploit and in turn avoid it altogether. Hence, why I said earlier “impossible” is far from what I’d describe the interaction – because there are so many ways to react accordingly. – which is why it not going to be always effective despite the huge pay off.
So at that point it boils down to skill being rewarded appropriately, hence it is emphasized as being more difficult than her sustain damage build. And that doesn’t sound like bad design for me, as it rewards your risk and skill appropriately.