No expert here, to which anybody who has seen my pit performances can attest
That said, here's my 2 cents:
Quick shut downs on engines that have been running full speed under load can lead to internal engine hot spots potentially leading to longer term issues. Metal, especially aluminum, likes to move with temperature changes and doesn't always expand or contract at the same rate in all places at once or always return to the same exact dimensions when the cycle(s) is(are) completed. One of the reasons we put an electric water pump on my buddy's lakester was for a more gradual cool down to help prevent that just in case.
Electronics, especially ECU's and injectors, like a constant full voltage for efficient operation. I know some seem to sneak by with constant loss systems but we run an alternator, feel the small loss in driving HP is well worth the increased efficiency in component operation which also leads to easier and more consistent system calibration and tuning.
Ed