I was actually there. The backlash against digital art usually came from:

• people who were otherwise already elittist towards one or two painting styles and media,
• art gallery regulars (they can’t sell JPEGs or PSDs),
• poor people as back then graphics tablets were way more expensive and alternatives to Wacom also worse (the patents for their battery-free pens haven’t expired yet), thus it was cheaper to buy paint and/or markers.