Very amusing, if a bit simplistic.
In reality it may well take a lot less time for the author to provide a summary than for the recipient to assimilate the same information from the detail, which difference could more than compensate.
"Well played" and the grumpy look are somewhat contradicatory. A reluctant compliment, but a valid one. Time is money, so it's better to spend grumpy's time (does he have a name) to read an attachment, than Dilberts time to write a summary. The word 'management summary' indicates which job is most overpayed :).
"well-played" ???? like your pay would ever be proportionnal to the work you provide, OMG get real ! that cartoon is just a troll, it is the right opposite of main line since ages : pointing out total absurdity of work life.
Don't know why but this strip reminds me the situation from Dilbert TV Series when the CEO was late for the "Akorn/GruntMaster 6000" name meeting and the point was that the boss was late because he's more important then workers and not because he's rude.