I am a freelancer in .net, the fact that telerik offers some certifications in their products convince me to use their ui as Microsoft third party controls... Especially when you are new in a developer market, even with a lot of years of experiences, it still hard to convince a customer that you have solids knowledge in different tools (I.e .net wpf, .net asp MVC, xamarin, etc) at the same time.
Developer Certifications are one of the best way to prove someone especially a customer that you are confident in this area.
I think Telerik developer certifications are also a best marketing plus value in opposite to other ui competitors.
So telerik team keep going on with certification offers in your different products.