Well, fluffwise technology was quite advanced till the Dark Legion came along. The AIs and high level computers practically went mad and turned upon mankind.
They switched off / sealed off / destroyed most of the high-tech and fell back to Cold War level. The megacorporations found some way to shield the influence of the Dark Symmetry, but they could not make it portable. They still use computer systems very well hidden and shielded but no way they are connected to the outside world.
The Brotherhood forbid the creation of machines "that could think for themselves" which edict Cybertronic broke deliberately. They also use some special construction or shielding to resist the effect of Dark Symmetry and the way they use AIs in the battlefields mean they are kind of successful.
They are slowly advancing again in technology, but none have the resources to equip the whole army to the highest level of technology (just like today). The special forces get the creme, and the Doomtroopers the experimental stuff..
Just my 2 cents