Hey Piyush,
I would say, this is one of those "just because you can, should you" scenarios.
Similar bit with VR Assignment Rules (scripted), you can technically set other values on target VIT records like you could with VR Risk Calculators (scripted).
The challenge with that, is it becomes tech-debt that you have to maintain - i.e. if another developer would have to jump in and review why a custom field was set to a value or not set, how would they ever know where to start triaging / diag from? Their first intuition likely would not be to go dive into an Assignment Rule or Risk Calculator first. I am also not sure how you currently document configurations, customizations and tech-debt - and if we are lacking in that space - this type of approach may not be the best path in terms of managing technical debt long term.
The other factor to consider, is if we use something like Assignment Rules (Scripted) or Risk Calculators (Scripted), to do something it is not intended to (like setting a custom field value) - we need to consider when those particular operations run (e.g. on record insert, on update of a certain field, when someone clicks the "re-apply" button). If we embed some special logic to set a custom field here - we may see odd behavior, have to maintain extra defensive logic in our script to determine when not to override logic. Don't lose sight of regression testing as well -> what happens when the business/stakeholders want to tweak the logic for setting that custom field, instead of regression testing just that one component (the custom field); now you have to regression test the entire Risk Score Calculator again, even though the change you made may not even have anything to do with the scoring logic - but we embedded an extra operation into the it. Then, the ultimate factor is performance as your data volume grows - when considering how these configurations work - and determining if it is really worth using these as the vehicle (i.e. Risk Calculator) to set a custom field value.
Hope this gives you insight on that.
