"We must love them both, those whose opinions we share and those whose opinions we reject. For both have labored in the search for truth and both have helped us in the finding of it." - Aquinas.
Snarly attacks and actual criticism are different things. One requires a bit more study and care than the other. The other is easier and perhaps more entertaining, which might be one reason that even campaigns that start off well regularly devolve into personal viciousness. Insults get the best applause lines. And sadly, pundits don't model discourse as they should.
Bernie bros. Hillaritarians."Qualified, not qualified." The competitiveness obscures the importance of building something together. Some feel this can be done within the existing dominant party; some are not so sure; but there remains the sense that bridges must be built.
The perennial problem is dismissing the humanity of other people. What sort of society can people with such a habit ever build?