Reverse voltage protection for Analog Devices’ family of protection controllers
Actually I think that none of the components you've circled in all the schematics are responsible for the reverse voltage protection at all (as you correctly pointed this out yourself in all three cases: "diode D1 blocks excessive positive voltage from the input supply", "R5 to block excessive currents from passing to the GATE pin in the event of excessive positive voltage at the input supply" and "a diode to block the excessive positive voltage at the input supply"). The secret actually lies more in the special arrangement of the diodes and transistors immediately near the input supply and the associated MOSFETs driven by them (D3, D4, Q2 and M2 in the first circuit, D2, D3, Q3 and Q2 in the second, plus the associated bias resistors of course). They ensure that voltage is only supplied to the circuits if it is of correct polarity. The 3rd circuit is a bit different in this manner (with the additional Zener diode D1 for regulation, probably because of this IC's wider input voltage range), but other than that the reverse polarity protection circuit is still the same (ensured by components D2, Q3 and M2). The mechanism of these circuits is explained in the LTC4366 datasheet you've linked in your question quite well I'd say.