Sure. Six jobs in six years is a red flag for me too. But 8 jobs in 12 years I don't blink at.
A few short tenures on a resume just means a few lousy or cheapskate employers. I see that often enough in great candidates that I don't weigh it in very much.
But yes, to your point, a resume with nothing but short tenures makes me think this person has been getting fired, or can't be satisfied.