You do if you want your assessment to be useful and appropriate. I cannot pretend to care about the fate of a company I have no stake in and then say my comments make sense. Just like I can give completely worthless legal opinions which amount to nothing more than "I like ice cream" and "I like the color blue" and who cares what I like?
The law cannot be interpreted easily without a legal degree which is why lawyers get paid such good money. I have an easier time making sense of medicine than I do law to be honest. I can interpret medical journals to a certain extent but law is like a totally different language to me.