Making something into a SRS card gives you a new option for dealing with the given inbox item. So instead of engaging with the item in the moment or deleting it - you have an option to "look at this later".
As the repeat interval increases exponentially - eventually you'll effectively delete the item without incurring the cost of explicitly doing so.
To think of it I've actually employed a similar strategy for the tasks - by rescheduling them to the future, though without the explicit exponential increase in interval.
It probably makes sense to keep the relevant inbox tags on the items to more easily distinguish various inbox types and various SRS prompts from each other