There are some good reasons that your employer want to wait and present everything in an official report. The example you give about black mold is a perfect example. I work in water damage restoration, so I have some experience in this field. So, you are on a job site and see what you assume is black mold. However, the problem is that without being a mold remediation specialist and running field or lab tests you have no proof that it is black mold. You are making an assumption based on a limited amount of information.
The problem in this situation is that if you tell the customer that they have black mold; and they freak out and immediately rip out their ceilings, walls, and whatever else they feel is affected. They then proceed to file an insurance claim, but the insurance company wants proof that they had black mold. They would either take some of the removed building material and test it, or worse yet if the materials have already been disposed, the customer is going to tell the insurance company that your company told him / her that black mold was present. When your company is contacted to provide proof for the insurance claim to back up your statement, it would be a very bad day for you.
In the above hypothetical situation, you can see how your statements can create liability for both your company and yourself personally. Anytime that you present yourself as a professional to a customer you must make sure to avoid making any statements that fall outside of your area of expertise or can not be backed up with conclusive proof.
Presenting a formal report allows your employer the safety net of making sure that they do not end up paying out thousands of dollars for a statement that the customer may take as misleading.
I practice this personally, because even though I am a certified water damage restoration / applied structural drying specialist, I have no certifications in mold remediation. Therefore, whenever I see what I suspect is mold. I inform and show the customer that there is suspected microbial activity. I also inform them that this falls outside my area of expertise. Additionally, I will recommend that they contact either a mold remediation specialist or an industrial hygienist.