Those drawbrigde was used inside the ruin at the great dam and made that base unraidable as long as people where logged in for a different of reasons. The drawbrigde itself was not the problem. Its the ruins layout that is causing the initial problems.
The ruin has a very narrow and long entrance tunnel. Those tunnel is not wide enough to place enough bombs closely on one spot to kill the gate off, therefore people can sit behind it and repair it after every explosion. The gate itself, no matter the hp, where also greatly protected by the mesh of the ruins. Because you could push it right into the mesh which leads to great damage reduction. People where able to also push the fence foundations deep into the ruins mesh, which made them greatly invulnerable to explosion damage also. Both the fence foundations and the gate where secured through the mesh of the ruin, which made it very easy to sit behind and repair.
The drawbrigde methode on this spot was not new, the 200k drawbrigde just made this spot even easier to hold.