They have a definition, they just won’t tell the users because it’s not a realistic definition and they plan to pull the rug out later on.
If third-party apps were only 3% of total traffic and reddit was willing to destroy its image and massively increase the viability of its only competitor just before IPO over it, I’m sure they’ll have no problem getting rid of whatever percentage of blind people who can’t see the ads reddit wants to serve anyway.
I wouldn’t be so hopeful, Twitch has pretty much remained unbeaten and the only “ad block” solution I’ve found still gives a 30 second interruption of the stream, it just doesn’t show the ad anymore. It’s why I don’t use the site anymore, even with Twitch Turbo as an option these days.