Even with this not just anyone can become a Symphogear user, provided that the subject a certain degree of compatibility, LiNKER can force that rate higher and bring them to the status of acquired candidacy.
Of course this process takes a large toll on the human body and it's not uncommon for subjects to receive a shock to their system which results in unconsciousness. Before the drug started producing results it left a lot of dead, or crippled subjects that demonstrated the dangers of the intense medicinal process.
It was for this purpose that LiNKER was further developed with an active time limit and method in which it was cleansed from the body. However these techniques were only obtained by data that Ryoko gained through leaking LiNKER into the black market, and by using it on the test subject Raine Amou unlike Rinne and Millay who are natural with their gears.