...because they were mad they spent a bunch of money on a lens that wasn't better and wanted to feel like they did!
Seriously, I had some people tell me that Zeiss lenses just suck, even the Master Primes (which I'm sure they've never used). After asking them for the merits of their comment, they said "they can't even get them to autofocus, who would use a manual focus lens?".
Yeah, that was responded to with, "oookay, I'm going -> this way now..."