Tanks do as much damage as carries.
Tanks should be tanks, and that should be their job. They should be designed to function as the front line, peeling FOR the carries, not being the carry. Right now tanks like darius, garen, and so many more build over 4k HP and still 3 hit squishies, or in darius' case kill one then kill them all. Tanks right now are unkillable, fine, let them be, but for the love of god why does a 5k HP garen have 500 movement speed and do 70k damage in a game after going even in lane.
or the old
.
is a bruiser.
If you want to count Garen's speed boost as a gap closer be my guest, but I'd say you need to redefine what you consider gap closers. Juggernauts are actually defined by having a lack of gap closers and mobility. Garen is the only one that defies this slightly with his movement speed, but outside of that good luck.
Are not what I would call bruisers. I can only assume you mean Darius' pull, which is actually necessary for the champion to function because if he gets slowed he's not doing any damage. at least if he's in range he can pull people to him. It's why Illaoi pulls champions to her, Garen gets to run quick to try and catch someone, Skarner gets a speed bump and a slow. They're necessary tools to prevent the champion from being entirely useless against slows, even though they're still rendered nearly useless by them against a competent team.
considered the greatest counter to juggernauts? Speed up allies, slow down opponents, shield any damage that might happen, prevent any actual kill.

then whatever you need more 9/10 it's not going to be high defensive stat items as the hp is more beneficial.




and 
, but Garen's CDs aren't really that problematic to require an extra 10%.