[johnywalker]

People use subdomain from free sites like WordPress, blogger, weekly etc because they are not ready to pay for a self hosted site

[skysnap]

I recently got one of the typeshare account. I realized that subdomains or getting domain makes sense in such case as it helps with search results and traffic.

[Treborika]

I think this is because most people aspiring to own blogs don't have that budget for hosting and buying their own domain names.

[raaman]

Why dont the bloggers invest a small amount to get their own domain name?

It is not a small amount as you think. Every year, you have to pay for domain name renewal and hosting, It is a recurring expenditure.

[oldbuddy]

You know you can always buy a domain name and redirect it to your subdomain site.