I love parsers for myself and my group. Main reason is because you can see where the group is lagging. Not from a blame standpoint, but just from a data standpoint. No deaths except for a team-wide enrage wipe? Let's look at the DPS numbers and see what's going on. Perhaps someone isn't using an optimal rotation or doesn't know any better. A teaching moment! Tons of deaths but DPS was decent? You can see total amount of deaths, and per person. This is usually not understanding mechanics well. Another teaching moment.

You get the idea. Parsers help you with this, and if you're a good human, allows you to try to help others with that data instead of scrutinize them.