PEA based fuel system cleaners like Techron are highly effective, at cleaning intake valves, on Non direct injected engines, and combustion chambers. GM also recommends it for when the fuel tank floats get sticky, so there has to be some pre injector attributes to the product as well, as the recommendation works, and not just on GM's.
I would not use Seafoam as a fuel stabilizer, and I do not believe claims written on labels. It is proven they will put anything on a label until somebody sues them for misrepresentation, and the only ones who profit from that are the lawyers. So there seems to be some collective understanding between competitors to just let sleeping dogs lie and milk the consumer with clever marketing and outlandish claims with no substance to back them up.
In fact with the content of Seafoam being a good percentage alcohol, I will no longer put any into my tank, though I have in the past without issue. Running it through the intake did seem to clean up the Idle a bit, but subjective seat of the pants "butt Dyno"s are hardly Scientific, especially with the human mindset of expecting results from effort or money expended.
Of all the Automotive forums I peruse, there are more fanboys of Seafoam here than anywhere else. On Other forums it is almost a despised product, so I find it amusing to come here and see it praised by some as the holy grail to engine maintenance.