Existing out-of-the-box functionality in Pega Markting 7.13 does not allow end users to create proposition based volume constraints for inbound interactions. The business requirement is not to offer e.g. Proposition X in any inbound channel after e.g. 500 accepted responses. However, Volume Constraints are taken into taken account only when .pyChannel is outbound i.e. in multi-channel outbound campaigns.
Thank you for reporting this product enhancement on PSC. I have raised a product enhancement request on our internal portal. The request ID is updated in the post under Related Support Case number field.