Why Using other people domain ?

because subdomain is a specific website within a larger one, I also promoted it on social media platforms. This allows me to target people who were specifically interested in the topic at hand and get them to visit their site directly instead of linking out to it or having them search for their business name.

Keep other people Brand Consistent with my demo project

Had Different Content On Each demo project

Better Organize My demo projects Sites

Targeting different geographic Regions.

Promoted my Subdomains On Social Media it help to domain also

I often find it difficult to manage domains on top of my demo website; using subdomains helped other businesses manage multiple websites without needing another hosting account and all of the overhead that entails.