can someone explain briefly why blockchain as a service makes sense? e.g. https://azure.microsoft.com/en-us/solutions/blockchain/

Based on my basic understanding I do see two major issues: 1. The integrity of the blockchain relies on (many) different parties that operate a copy of the blockchain independently. If someone offers this as service this prerequisite is violated, isn't it? 2. The implementation is controlled by a single party and not implemented by a third-party which is not directly involved in the business.

All in all, Blockchain as a service seems to be just another (business) term for a trustee protocol.