What is the relevance of fulfillments at BPP level?

[joffinjoy]

As per the current 1.x core-spec schema, fulfillments are found at two levels. At BPP and provider level as shown below:

{
	"catalog": {
		"descriptor": {},
		"providers": [{
			"fulfillments": [],
			"categories": [{}],
			"items": []
		}],
		"fulfillments": []
	}
}

What is the relevance of fulfillments at BPP level? We are trying to understand the use-case in terms of DSEP.

Swagger schema explains it as:

Fulfillment modes offered at the BPP level. This is used when a BPP itself offers fulfillments on behalf of the providers it has onboarded.

But what does this enable? What is the concept of fulfilment in DSEP that is independent of provider?

cc: @ravi-prakash-v, @aks30, @vijiurs, @kiranharidas187