Theory: If people read conclusion first, then people tend to evaluate whether they agree or not after reading conclusion. Emotional reaction toward conclusion will bias interpretation of arguments.

The remaining arguments are more likely to be accepted or rejected based on what you know conclusion is. So instead of asking "is this true", people will start either with "I am looking for nitpick cause I see this is going toward bad conclusion" or with "yeah sure, it shows what I think".

However, they will still feel like they evaluated arguments on merit. If the conclusion is last, people can and some will go back to arguments to bias them, but it is easier to see what they are doing.

While the solution may be valuable, there's more value in reading the work to get there. Rarely is the value a decision, inasmuch as the path to the decision. By first declaring a solution to a problem, you're priming the other individual. Depending on their personality you're priming them to be for, or against your decision.

By articulating the reasons, methods, and considerations that went into a decision, you're slowly and softly building an argument. Individuals are less likely to have an instinctive reaction to something this way. At the very least, it's proven (yes, as in measured) to be the case here.

I have experience at several companies with many different cultures, and I don't know of anyone who likes to slog through the details before getting to what the final problem or solution is. People just don't have time for that. Putting the important part first serves the dual purpose of quickly informing people who aren't interested in the details, and telling them up front why they might care about reading the details.

It's like having an abstract or a blurb to briefly summarize for management.

Similarly, if you need someone to take action based on the result, you don't put it at the end where nobody's going to read it. You put it at the beginning, first thing, and then build up the background.