You have to understand in Warriors Orochi, characters are split into 4 classes. That character Jeff was playing is a power type character, and power type characters don't flinch when attacked. Warriors Orochi 3, especially Gauntlet Mode, gets annoyingly hard.
Dynasty Warriors, and the other Warriors games, are perhaps my favorite franchise of all time. I'm not delusional enough to believe its the best made game and I understand its not for everyone (as do most of the fan base, in my experience), but I find most people who are adamantly against it don't know anything about it. There are a lot of things at play in these games that only people who put the time in to find are going to know about, such as (in the case of DW8) weapon switches, the different way each weapon works, EX attacks (two per character), musou attacks (three per character), some characters can jump cancel.
Again, I don't think its the best game ever made. But it satisfies urges, at least.