"Never let an abuser take you to a secondary location": It's OK to offer an app, but if a site is pushing, pressuring or forcing you to get one, it's almost certainly because they want to do something abusive that they currently can't.
Installing an app is a matter of trust; trying to push me to install one against my will is the best way to demonstrate that you should not be trusted.
(Interestingly, I've heard a stance from technically well-informed iPhone users that don't see an app install as a large trust decision, because they assume that iOS is actually decent at protecting their privacy and rights in general. I don't know if that's true; on Android it certainly isn't.)
Installing an app is a matter of trust; trying to push me to install one against my will is the best way to demonstrate that you should not be trusted.
(Interestingly, I've heard a stance from technically well-informed iPhone users that don't see an app install as a large trust decision, because they assume that iOS is actually decent at protecting their privacy and rights in general. I don't know if that's true; on Android it certainly isn't.)