That's a great question, since the genesis of this was the domain name, which no one using the app will care about or visit. That is, the only thing that was actually needed here was the trademark, it appears.

Especially odd considering that Friendster began at a time when social media on phones was unheard of.

I remember when we considered a website that tells the user to download an app an anti-pattern (e.g. earlier versions of iMusic).