I mean, it can be both.

Factory farming has been around for more than 100 years. Upton Sinclair published The Jungle in 1906.

The meat industry has done a pretty good job keeping the horrors of slaughter houses out of the public eye, especially in the days before almost everyone was walking around with a video recorder in their pocket.

I'm sure exposure to what's really involved in modern meat production has increased the popularity of veganism, but veganism has been around for at least a thousand years.