Hello,

There is no disadvantage. It is just an entrance exam. Score which candidates secure shows their knowledge level. Candidates try to score best in exam by giving effort. Candidates who  can remember or understand easily , the process becomes smooth than a student who struggles at first and have to more effort to reach to a level.

Process is same for everyone. it is easy for some and hard for some. those who holds patience and struggles continuously performs well.

it is your choice is you want to give or not. There are colleges who hold their own exam for admission into Master's program. You can go for those also. It  is not mandatory to give GATE exam. GATE is a national exam which is accepted across India. and have a high recognition.

Hope it helps!