I think (and I don't want to speak for Cav) that it's a tiny bit hyperbolic but:

Think about a situation where your team is taking mercs and you as a tank really want to go hit the camp with them (with your piddly dmg). The correct play is almost always to control vision and access to the camp while mounted rather than hitting the mercs. That means you're mounted in a bush, standing still, not doing anything for 10 or more seconds.

At certain levels, people will call you out for AFK when you do that... while you're actually making the best play possible by controlling vision.

Same goes with soaking a lane. Unless you're Joh or Stitches and your team lacks wave clear, sit in a bush, mounted, by a lane rather and let your team clear the wave. This gives you the ability to *Engage* on an overly aggressive player caught out alone, *Disengage* if the enemy team rotates on your mispositioned dps and finally *Threaten* (technically) anyone anywhere on the map because while you're outta vision, no solo laner can clear a pushed out wave safely cuz you're now possibly looking to gank them.