Eh people can do that with any style though. Anybody that has mastered swingblock can just facehug and spam combos and win against most people.
Blue has almost no recovery window on its swings. Others have fairly long ones (Cyan is probably the only other one with actual cancer qualities in regards to its startups). Even if you do manage to get a swing in during that, its defense rating is so high that the damage you do doesn't stick. Also ends up leaving you open to being locked up by the block anim garbage.
Blue seems to predictable as hell though since it only has 2 swings
Only predictable if the person is just doing the same ones over and over the entire time. Considering Blue also has short wind-ups (not even counting more difficulty from yawing), predicting it is in the same realm as Cyan. The consecutives are also basically instant regardless of which swing you pick so that throws predicting out of the question (again, you can basically only PB its consecutives if you happen to guess properly or the person is repetitive, which applies to any style).
and can be beaten pretty easily if you keep your distance and stop them from gaining too much momentum.
Blue has no slowdown on swings while moving around. This means that you can neither outrun it if you're in range nor catch it if you're out of range. This also means that if they do shadow-shadow swings to any degree of competency (whether intentional or not), it's even more of a headache than usual.
Combine all of the above and more with its damage on PB and you just get a good recipe for cancerous "dueling". Also see what
@StarWarsGeek said. There's people who are terrible duelists that I can slaughter in like 5-10 seconds but when they use Blue (while still playing terribly) it suddenly takes 30+ seconds to kill them (assuming they aren't playing super passive) and it's an uphill struggle the entire time.
It's basically the equivalent of 1.3 Cyan minus the ability to rely (somewhat reliably) on counters to kill it.