Proteoglycans vs Glycoproteins
More context would be helpful, but it's possible the data from the Quora post was incorrectly transcribed from a table on this biotech site, which states that the carbohydrate content of proteoglycans is 50-60%, compared to 10-15% for glycoproteins.

However, the first comment on that page suggests that the table was initially incorrect:

Hi Anne,
This is a great post, but the numbers for the carbohydrate content are reversed. It’s 50-60% for the proteoglycans and 10-15% for most common glycoproteins (and things like uromodulin and most mucins would be 30+% sugars).
Best,
Jared Gerlach

So that may be the source of confusion, here.  It seems the commenter is an expert in the field of glycan research, so the table is likely correct.