Why I can RW concurrently to BlobAssetReference?

Why I can read and write concurrently to BlobAssetReference in IJobProcessComponentData (I suggest that this job is parallel)?
It is awkward for me. Is it bug?

Blob API is very intresting, it is basicaly what I need - data that is shared from one side, and that is burstable from other side. But I have a suggestion that this type of data must be ReadOnly in this situation.

And I think that it is good to have type like IConstValueSharedComponentData (true enterprise name). That does what it must, contains some shared constant blittable characteristics of bunch of entity that can be used in jobs. I feel that Blobs can do the same, I just don't understand its behaviour.