Actually I'm surprised. In the 15 or so matches I've played, turtling has happened twice (and only once led to a win). Usually people would rather stick to the center and have quick, fast, brutal matches. Turtling doesn't work as long as the non-turtling team has a coordinated effort to kill the fang carrier. He's losing health every couple of seconds anyway; swarm him and down him and keep the fang out of the turtle team's hands for, what, 15 seconds? And it respawns in the middle. It's pretty easy to do.
I find that odd.
Without a doubt though, turtling is the most effective strategy for winning Black Garden. I go into a rather broad explanation in my linked post, but there really is no reason a turtling team should ever lose agaisnt an evenly matched opponent.
On uncoordinated teams, what ends up happening is that the enemy streams to you in sets of 5 or 7 at most, and so you always have the number advantage.
In coordinated fights where the enemy comes at you with a full force of 10, you still have a massive advantage. First you have the high ground, which lets you pepper the enemy before hand, potentially killing off one or two of them. Then when they come to fight you own your home turf you have an LOS advantage with the tree and rock, as well as constant reinforcements from the spawn. Unless they take less than 30 seconds from the first kill they make to capture the fang, they will be outnumbered and should lose assuming equal teams.
It's also nearly impossible for them to take the fang. The defense can position the fang behind the rock, blocking enemy ranged LOS and making it easy for them to repick up. Even if the enemy can get los to the fang, they are a a disadvantage when it comes to stopping the turtle from repicking it up. The defense will likely be right on top of the flag, which means they have access to both ranged and melee characters interrupting a ninja. The offensive team will likely only have access to ranged characters. And it can be hard to burn through that shield.
Any type of drawn out fight or even battle massively favors the turtling team. Also turtling doesn't have to mean keeping your entire team next to spawn. Turtles can afford to send out 5 or even more troops to weaken any advancing force, because even if their troops die they will respawn before the enemy reaches the fang.
As a side note, while wardens may be OP pvp healers (at least at low levels), purifiers are stupidly good for winning getting the flag. That shield makes all the difference in the world. As long as it is up you can take hits while still capturing the fang.
A bigger issue for me were queue times. Even with a ton of players on this weekend, queue times for me frequently went well over their estimates (ie, the estimate is 8 minutes and I only got into a warfront every 20-25 minutes). very annoying.
I'm not sure how typical or atypical my experiences are, but every time I queued for a warfront I got in in less than 30 seconds. This is probably due to playing Guardian. Other relevant information was that I was on Lotham server playing around mostly 6-10 cst.
I assume faction imbalance is the reason to blame, and hopefully that will be fixed by release.