That would always by definition block all third parties.
Think of the reddit example from the person you replied to: there was a huge outcry when reddit announced shutting down their lower API tiers.
Either information is free to flow or not at all, there is no middle ground.
With that in mind: I’m sure they thought about it and decided to prioritize transparency she flexibility over security. Personally I support that decision.
Seems like a historic artefact to me as well. And one of their mentioned points was “no sync via http” which even for 2006 makes me… hesitant.
And their history section ends in 2007, couldn’t find a feature comparison in their quick start guide.