Because seizing and destroying enemy infrastructure to cripple their ability to keep fighting you isn't a thing. Not like the USAAF spent months bombing German fuel dumps and railroad yards or anything like that.
SciFi:
Early Heinlein. Starship Troopers, The Puppet Masters, The Moon Is a Harsh Mistress. Ignore Stranger in a Strange Land, it's fucking weird and it drags. The Number of the Beast is pure lazy shit and a prime example of why authors should be constantly critiqued so they don't get big headed about whatever weirdness they have knocking around in their minds-- in Heinlein's case, teenage girls and incest vibe shit.
Philip Jose Farmer. I mentioned Riverworld and World of Tiers, both worth reading. Be aware that while he was good at writing stories he was not good at ending them.
Frederick Pohl. Heechee series.
Ray Bradbury is much less science and more fantasy and horror in many aspects but a lot of his stuff is really good. Fahrenheit 451 and Something Wicked This Way Comes. His real strength was his short stories, though-- The Illustrated Man, R Is For Rocket and The October Country spring to mind-- stories like Kaleidoscope, The Long Rain, The Veldt, The City, Frost and Fire.
Larry Niven and Jerry Pournelle collaborated on some really good stories. I've read some of Pournelle's stand alone stuff and I have to say I didn't care for it; never read Niven stand alone but I've heard it's good. They put out some very good stuff together though, as long as you remember to IGNORE ALL THE SEQUELS (except maybe The Gripping Hand).
Inferno-- Good. Escape From Hell-- Bad.
Legacy of Heorot-- Good. Beowulf's Children-- Very bad.
Mote In God's Eye-- Good (it has been declared by some to be the best scifi novel ever written; don't really buy that myself but it is good). The Gripping Hand was a much lesser offering IMO.
Some of their other stuff: Footfall is interesting and Lucifer's Hammer is extremely good.