Description:
Meme format image. The top half has a picture of Star Trek: The Next Generation's bridge crew with the text "the prime directive forbids us from interfering. We cannot share our technology". The bottom half has a picture of Stargate's SG-1 team and the text "all your gods are false. Here, take these guns."
Jack's whole "This is a weapon of terror: it's made to intimidate the enemy. This is a weapon of war: it's made to kill your enemy" speech made sense though. The goa'uld were so damn full of themselves after they'd spent way too long subjugating some poor backwards fucks whose most advanced military tech was pointy sticks, that their main weapons weren't actually all that great for murderizing their opponents but worked wonders to keep the poor backward fucks in line. On top of that the armor that jaffa used often seemed more showboat-y than functional, and the personal shield kajiggers the system lords tended to have were honestly a bit shit in many ways, sort of like Dune's shields but worse.
So hurling a piece of piece of lead at supersonic speeds at a hapless wormy dude is definitely going to be pretty effective in many cases, and their return fire – if any – is going to be more spray'n'pray than anything else because lol good luck aiming with a fucking hip-fired stick, lasers or not.
Yup. The movie basically set the tone that the galaxy was ruled by decadents that were kind of unaware and feckless when it came to novel challenges.
On top of that, SGC figured out that sending scouting parties of 3-4 people was insanely effective at shifting the balance of power across the whole flippin' galaxy. And that was just with conventional ballistic weapons. It makes complete sense to arm counter-insurgents with what was already working, on a much bigger scale. It gives Earth and your exploratory efforts a lot of breathing room on the cheap.
The show extrapolates from there, but does the odd thing of having to make the Goa'uld super effective at interstellar warfare, to explain the conflict with the Asgard. But by that point, the SGC has looted enough tech to build a single ship, along with a huge chunk of Robotech's storyline, to save everybody.