Is suffering spiritually beneficial? If so, precisely how does it spiritually benefit someone to suffer? If not, then why not?
Being illusionary, I don't see suffering as beneficial, nor rational to conclude that it could be.
But given that many of spiritual/religious beliefs co-mingle physical existence with spiritual reality, I do think it is plausible to see what the context is to determine what the actual (alleged) suffering entails and how that plays out, to then possibly determine if it is relatively beneficial. Relatively beneficial would still be illusionary in my understanding, but that perception of benefit could matter a great deal to the person identifying with the (alleged) suffering and to those able to observe the situation (i.e. friends and family).
I believe that anyone who experiences suffering, and keeps an open and observant mind about it, can easily note that suffering focuses them on themselves, and is thus self or ego-aggrandizing.
And if those people are lucky enough to have experienced at some time in their lives a certain kind of love, then they can further note that suffering does not teach them anything that can be called truly profound in comparison to what that love has taught them. In short, there are few or no spiritual benefits to suffering.
At least, that's how I see it based on my own experience.
I recently had physical ailment that lead to own perception of (physical) suffering. There were a bunch of things I was processing, and one of them was me being analytical on the place (on my body) that ailment was occurring. When connecting with Spirit and having dialogue on it, it then became solid realization of how I could do things differently going forward. First (though not foremost) was having medical doctor weigh in as the physical discomfort was strong enough at points and my thoughts of suffering at points were nearing the unbearable mark.
Anyway, for me the context does matter, because of Spirit connection and my theological understandings. I don't receive messages from Spirit that it is illusion because Spirit knows I know this and because as much as it is illusion, part of that is how much I buy into the illusion, which in this case was enough to matter (temporarily). But given the entire context of the situation, it has lead to slightly better care of myself going forward. And I say slightly cause it is thus far short lived. It could become significant, but I might not know that until months/years from now, and yet also not really known how it would've gone had I remained stuck to the other path. I do not readily identify that I was doing anything (significantly) wrong to warrant the ailment, but what I was doing was making it so if an ailment did arise, it would be harder (conceivably) to get rid of.
So, the recovery process from perceived suffering certainly does have benefits. Can be easier to remove certain spiritual blocks (to greater awareness) by experiencing recovery, especially if willing to process it spiritually. Not so much if processing it entirely physically, as that greatly limits perspective.
The only benefit that makes a little sense to me regarding suffering is it does force you to rest, and deal with latest (likely self induced) forms of stress in a different way. But even with that context would matter and surely no one actually needs to be forced to rest. Though, given allegiance to the illusion/physical, it sometimes seems like we need to be taken down in order to remind ourselves of the importance of rest.