It used to be a bigger deal (when digital cameras started being used) since people felt like digital video didn't look real/as good - movies shot on film were generally better looking (as crews were used shooting with it and digital video wasn't as sophisticated as today) and HAD grain.
It might be that there is a large part of the population that still has that association.
Cinephiles are also more likely to watch older (i.e. with grain) movies that ARE well shot and beautiful (which is why they are classics and watched by cinephiles) and not see bad film movies, only the cream of the crop, while being exposed to the whole gamut of quality when watching todays movies shot digitally. Would reinforce that grain = good while not being necessarily the case - and their opinion might be heard more than gen pop.
At any rate, it can be a neat tool to lower sharpness!