When we are spending times with friends, we can spend hours discussing about almost any topic. It is not mandatory to have data, only respectful arguments that can support our opinion. The opinion can be based on your personal experience or in someone elses that you try.
But when you try to change things, when at work you want someone’s help, it is not enough with a belief, a feeling, an idea. You need to bring facts. As many as you can. This is not working, this can be done in a better/Different way, here I have the data to support my words. We need to do this change, we need to have this tool. This are the data we have to support our statements. Or, if we had the data we would be able to act over this different issues, but we are not able to obtain the data, that is why we need to build a reporting tool.
The difference between an opinion/idea and a fact is data. It will help you to sustain your requests, your arguments and get the help you need (or at least try to) or prove yourself you were wrong when you first brought to the table that idea that felt soooo real.
Data can be useful, it can bring light to foogy zones.