We blame and criticize others because we don't like suffering. But if we don't like suffering, we should not harm others and create disharmony; this is what interferes with our happiness. What we want and what we are doing are opposite.
Of course, this doesn't mean one can't point out others' mistakes at all. But when you do, as much as possible do it with loving kindness and compassion. For the sake of others, one can point out mistakes and make suggestions—this is how you discuss and communicate according to Dharma. This way there is no danger for oneself; one doesn't create negative karma, which throws oneself over the precipice of the three lower realms.
Lama Zopa Rinpoche
The Faults of Criticizing and Blaming Others