It's only declaration by fiat if you stop reading at the end of the title. Should authors add a qualifier like in my opinion to every statement that they make?

It's only declaration by fiat if you stop reading at the end of the title. Should authors add a qualifier like in my opinion to every statement that they make? The essay structure you're criticizing is exactly how I was taught to write from primary school through to university. You start with a title or hook, introduce the topic and propose a thesis. That is followed up upon with supporting arguments for the primary claim.