If the expectation doesn't meet reality then there will be disappointment.
Unfortunately the spin doctors create an expectation that is not a reality. A view that creates a sense of entitlement.
The staff of an airline are not perfect. They have bad days, often not paid well, made to work harder than ever, and treated miserably by some self entitled travellers. They are less than perfect interacting with less than perfect humans. They can try to create an air of servitude in line with their training, but stress will reveal cracks in the facades of unnatural play acting.
I have had terrible experiences on so called 5* airlines EY. UA, BA, LH and VA. Unsatisfactory on MH, LA and others. Mediocre on QR and QF. I have also had great service on the same airlines.