I have just an intuition that the carbohydrate part of glycoproteins help them to fulfil those tasks like in plasma membranes. You can also get many more receptors if you can use carbohydrates too.
For instance, glycoproteins are necessary in recognising white blood cells. Antibodies are examples of glycoproteins. So they play a crucial role in our innate and adaptive immunity: MHC interaction with T cells in adaptive immunity. Other examples: necessary in platelet aggregation and adherence, components of zona pellucida and connective tissue. Some hormones are also glycoproteins so necessary in humoral adaptive immunity: FSH, LH, TSH and EPO.
But why glycoproteins are "better" than proteins without carbohydrates moiety in fulfilling biological tasks?
I still see that both are important, but why the one is better than the other one.
In other words: Are there any biological tasks that only non-glycoproteins can fulfil, not glycoproteins? Are non-glycoproteins necessary in some essential biological tasks?
I think the answer to the last two questions is "yes", so why would one say that glycoproteins are better in fulfilling biological tasks than non-glycoproteins.