ATI at its worst had 35% marketshare(and at best 50%),despite the same memes happening back then and Nvidia having the NV FG all around the interwebs. AMD by extension saw its share drop to 17% and is now around 29% which is historically very low for ATI/AMD.
This is not all down to the physical products but the way AMD launches them,and makes them look worse than they are. People here are going on how inefficient GCN was,but forget outside Tahiti,the other GCN MK1 GPUs were very competitive in performance/watt and performance/mm2,but AMD started to see a decline even back then. Part of it was because they utterly screwed up with the switching mechanism in laptops IIRC,whilst Nvidia managed to get theirs working better.
The fact of the matter,you need to look at the last few AMD launches to see why people are sticking with Nvidia - there is always some issues,and Nvidia by extension might have their own but they tend to deliver more often,unlike AMD does.
I mean FFS look at that article on Anandtech when AT was invited to AMD HQ to look at some Carizzo laptops?? AMD was going on how they were not getting traction from OEMs,so they had to end up having SKUs they offered not working in the optimal way,ie,like having single channel RAM. Except a number of the laptops they had were not production representative examples and could run dual channel memory. In fact one of the laptops they touted as being only single channel,was actually reviewed by NBC in dual channel mode with RAM sent by AMD to them.
At this point,it shows the issue here,they miss on details which means competitors can jump on using social media or even in reviews. Look at the R9 290X - they offered a bloody "QUIET MODE" on a cooler which was barely enough on normal mode. Nvidia then bought an example,saw it was downclocking in quiet mode,and then informed reviewers of this and sent a few cards off for free.
The R9 290X/R9 290 should have been the next HD4870 FFS.