I don't think it's evidence of that. I already know of end gamers that rage quit over the issue. The problem is that some people come to the conclusion that it is nearly impossible to get missing mythics AND reliably chase new ones during exclusive weeks. No one has that impression of other rarities.
As a completionist myself, I don't believe I will ever get the two mythics I'm missing since I use the "hoard for exclusive week" strategy. This fact irks me. However, I can ignore those two for now. If I were missing substantially more, I'd probably lose interest in the game because of that feeling of not being able to at least work or pay to get them.
I have no problem with long goals that I can actively work towards. However, the mythic situation is problematic and filled with frustration. Obviously, Sirrian understands this now since he is open to discussing crafting.