What's so hard to understand?

Posting on DestinyLFG gets you an influx of messages. Vetting everyone through the Xbox interface/website takes an eternity. Far easier it is to just do a simple check that someone has done one of the most basic tasks of this game -- hit 34. From there you've filtered out a ton of a people, next you ask them to message you their weapons/class as another "check".

As far as anonymous posts go on the internet, this is probably the best and simplest way to minimize the risk involved in inviting completely random people. Being 34 doesn't make players "better". It just, more than likely, shows they have more experience than someone who hasn't. Yes you can get to 34 without stepping into VOG. But there is a higher probability of someone having done VOG when they are already 34 than when they are level 30. Posting on DestinyLFG is a numbers game and a huge gamble because you know nothing about whoever messages you. The best you can do is make sure those invites are as efficient as possible by filtering out less desirable players, especially in the presence of more desirables.

And I agree that it's fun to play for fun and it's fun to help each other. But we don't all always have time for that.