This is where you don't understand!
Every country has different ratings based on many factors and there are several international ratings on a country's credibility.
Some has high grading like Singapore, UK, Switzerland at AAA in the Fitch rating against MY's A-.
AAA are the best quality borrowers, reliable and stable and international banks will fight tooth and nail to service this country..
Once you are on a lower scale, the interest on the borrowing will usually be much higher and maybe only certain banks are willing to service.
Take a big loan and you'll be in big trouble.
Good example 1MDB, the interest generated is as much as USD300 million/annum which means about USD1 million per day!!!!!
And worse, 1MDB had already defaulted TWICE this year and this is definitely bad for the country's future borrowing and its rating!
Hope you now understand better.
Then how come those countries that have AAA, their debt ratio also big?