I agree, you earn diamond status for the benefits, and as a result I also put 90% of stays Hilton way, you get into the programme. The other stays are typically because Hilton "doesn't fit", but given preference I always use the brand.
As a result, it is a fair expectation to be treated well. It cant be amazing every time, but it should be above the norm at least. It pains me when it isn't!!