I was listening to the Cultcast, and they brought up a great point. The 2016/2017 significantly negatively changed the perception of the butterfly keyboard. The numbers can be very subjective, but when you are working with the numbers of units sold, even an incredibly small percent of those units is a lot of units.
Example: Numbers used for arguments sake, If a million MacBook Pro's with the Butterfly Keyboard were released and sold, and simply 1% had the failure, that's 10,000 MacBooks with defective keyboards. If they fixed it in a revision and .5% still had issues, 5,000 still complain.
Now they try to fix the perception of the butterfly keyboard, but the reputation is already out there. They revise it even further, and so few have the issue even compared to the 2015, the bad perception is almost irreparable at this point. 2019 they revised it again, and added it to the covered keyboard list to be proactive, and the perception is they did it anticipating its already going to be a problem. It's a no win.
I think that's why they are rumored to go back to a scissor design which will likely be thinner with less travel then the 2015, but more travel than the butterfly.....try to make the best of both worlds.
My opinion has always been, I prefer the lesser travel of the butterfly design. I have had no issues at all with any version I've had with it, but that is just my opinion, and I am thinking I am in the minority in that thought.