When it comes to domain name registrars, many have loyalty to one or just want the organization and ease of management to just one provider.
Some use registrars for different extensions, your favorite might have the best .com, net, org pricing and privacy for free but they are too high for your interests in new gtlds or exotic cctlds.
I think if you are a .com only investor the number tends to be lower.
When you invest in new gtlds there are so many different deals. You need more registrar choices.