this procedure was put cause many pilots had joined qr and jumped shipped after getting their rating so they want to minimize their loses ,i dont know personally if its a good idea or not but if ur a new joiner it will be the same old salary for 18 month and then u get the new pay scale .which isn't so bad if ur jobless .on the other hand getting good qualified pilots will be difficult to attract to qr so i guess they looked at their options and choose this one coz they have a lot of applications especially from mexico where i guess one of the airlines let go of 100 pilots or so .
so new joiners and jobless take the offer .
new joiners with a job look at ur options and decide whats best for u but all airlines are like banks they have a catch somewhere that u don't see or realize till ur in the company ,i heard and i am not sure that some companies make u get a bank guarantee for the type rating amount and keep it till u complete 3 yrs and then get back with interest and others have different ways .
for qr they should make the airline more attractive for pilots to stay but its also not the airline by itself that need to do that but the country as a whole have to be attractive and thats going to take a long time .