How could an organization dedicated to a topic filled with people who dedicated their life to said topic be trusted to have a balanced view of whether or not that topic has an impact? Just purely from a conflict of interest perspective, it seems similar to asking for a balanced view of religion from the 'international panel of priests and pastors'.
Climate scientists are not dedicated to advancing the idea of anthropogenic climate change, they are dedicated to studying the climate, where ever that leads them. If this were not true, then some of the contrarian scientists in the field would have much stronger criticisms of the work. As it is, their criticisms are relegated to rather minor details, without any good rebuttals of the primary thrust.
If you want to make the claim that the IPCC is not balanced on this, then there should be much stronger criticisms of the science in the IPCC, rather than the easily knocked down trivialities that appear in denialist memes.