There are three reasons:
1.GDI develops slowly, and can only defend a large number of alien arms in the early stage (unless it fights with people).
2. The strength of the alien air force is very aggressive to GDI, and GDI's air defense capability is very poor in both the early and late stages. This is not what one or two people said.
3.GDI is not suitable for protracted war, and it is not easy to occupy mines. But GDI is the most expensive, and the growth accelerator of aliens is a cornucopia. GDI will be too much for a long time, and it will be exhausted.
When you say light weapons, I guess you may mean three feet.
Its range far exceeds 100 mm, and it is the second largest unit in the ground forces. As an advanced unit, it has the longest range. The only thing that can be farther than it is the beam of NOD, but the defense is far less than that of tripod. The only defensive building that can range farther than him is NOD's bright stone tablet. Of course, you can only charge with a light beam.
GDI MM can play three legs, but if there are too many opponents, MM's mobility is poor, which is very unfavorable. Therefore, GDI can say that there is no fixed number of three legs, only tactics, and nothing else can resist the attack of three legs. A well-controlled player can knock out a sonic tower with one leg unscathed. Of course, after all, three legs are equivalent to tanks and can be bombed by planes. It's a pity that GDI's Firehawk is not very powerful. Of course, they are numerous ... NOD bombers are very good at bombing vehicles. MM is most afraid that three such planes can blow up one. If the air defense is not strong, it will be bombed for nothing. The strongest nod I have ever seen is that the whole air force is playing GDI, and your harvesters are afraid to leave the house. If you go out, you will die. People have circled over the mining area, and three booms will make you disappear. GDI can endure this torture several times. Don't send fighting dogs to accompany the harvesters to mine? That costs money ~ you are as careless as sending a fighting dog, how many can a Scorpio give you ~