It all has value, absolutely! The problem is presenting it as "solution to fake news". This is setting the expectations way too high, and is an impossible bar to reach through that approach.
With respect to media environment being technological - it's true, but cultural effects still dominate. If Facebook, for example, added some kind of "fake news" indicator on stories, would it help? Probably not - people who read and reshare them will just ignore it, and would describe it as some kind of nefarious attempt by "Silicon Valley liberals" to push their world view on them. Eventually, someone would make browser extensions that would disable it completely, and people would install that.
Suppose FB just starts censoring such stories outright? Then they'd simply be shared somewhere else, on a (possibly new) social network created to cater to this freshly alienated by huge market. I would imagine that the guys running Breitbart would just love to give it a go.
Obviously, there are certain social effects - networking etc - that make existing platforms entrenched, and provide barriers to entry for new competitors. But the barriers are not insurmountable, and said social effects can be negated by sufficient amount of inconvenience caused by staying. I assert that any technical solution that is strong enough to actually solve this problem would constitute such sufficient amount of inconvenience.