So you're judging the abilities of the S'pore soldiers against
that of the MARINEs based on the duration of their trainning. Hmm!
Fair enough if you put it that way. 
But MARINEs are lifer while the S'pore soldiers are just doing a
service to the country. And for that duration of service to the
country, they are sacrificing their safety for the defence of the
country which from my personal point of view deserve respect for
it. 
As for your concern about guys getting rank through their grades,
I'm not sure what it means. But a rank is still a rank, just as an
officer who doesn't deserve a salute is still given one. In the
end, the one with the rank has to be responsible.