@Heathcliff
- a plug-in to give you a more informative YouTube experience
What better information can they provide than Youtube's analytics?
Various tools to help recommend tags and descriptions, far better insight into other people's videos, information broken down by the minute to better plan when to upload, batch uploads/ comments, etc. Granted, most of the same features can be found for free (or at a low cost), but some networks offer them as part of their service.
If interested, I'd recommend giving TubeBuddy a try.
- a community forum with other members of the network
That's not a benefit, you want organic subscribers those who are purely interested in your content ---btw YTTALK is the best community for Youtubers
Yes, this place is the best overall community, but sometimes people like options and, if they weren't already here, a network forum "might" be a decent option.
- more licensed music options
There are enough options out there on the internet, instead of loosing revenue because you give away a peace of your cake to a netwerk you can buy great audio instead at audiojungle
I would say that the bigger issue would be when someone decides to leave a network and then realizes that they no longer have the rights to any of the music they've been using, but that doesn't change that many networks offer music collections greater than what's available on YouTube.
- you may not have to wait to pass AdSense's $100 threshold to receive payment
I prefer to be payed 100 dollars at once than micro-chunks.
That's a personal preference. There are plenty of channels out there who will never reach the $100 threshold, but wouldn't mind making $20 here or there.
- more methods to receive payment (PayPal, etc.)
For each transaction through 3rd party you "pay" fee
...and, in the countries where AdSense isn't, that's the best option available to them. Likewise, not everyone has a bank account and PayPal (or similar) can be very convenient.
As I said in my post, I no longer understand the need for networks any more, but people still continue to use them and most will site the above reasons as the benefits.