Compassion is not the same as politeness or good manners; compassion involves understanding suffering in ourselves and in others and actively desiring to alleviate it.
Another way of looking at it is that compassion presents an optimization problem: minimize suffering. If we’re not building technology with an eye toward minimizing suffering, what’s the point?
Compassion often demands candid and direct communication, so being “fake nice” is not compassionate.
RTFM makes the assumption that the person is motivated by laziness or perhaps even a desire to waste your time. It leaves no space for understanding the person’s true motivation in coming to you for help or even what they’ve tried so far.
The implication of RTFM is that the asker could have found the answer to the question without asking, and is therefore violating some social law by asking. This can easily stir a sense of shame in the asker.
Shame is such a painful feeling; it is cruel to knowingly encourage it in others.