I see wonderful symmetry here. There are TrendyCos (hot startup unicorns), BigCos (established companies like google or amazon or microsoft) and UnknownCos (not in the limelight so there is not much information about them). Likewise there are TrendyDevs (hotshots who produce one heavily github-starred framework after another), BigCoDevs (multiple years of experience at one of the BigCos, probably were responsible for some important part of one of their numerous services) and UnknownDevs (been there done that, hard to say).
And here is the rub. There are certainly many undervalued gems among UnknownCos and UnknownDevs but also many abysmally bad workplaces and programmers. So you either have some inside knowledge about them (a referral, an acquaintance working at UnknownCo), have some magic method for separating the gems (like tptacek claims to possess) or it is just too risky to consider them.
And here is the rub. There are certainly many undervalued gems among UnknownCos and UnknownDevs but also many abysmally bad workplaces and programmers. So you either have some inside knowledge about them (a referral, an acquaintance working at UnknownCo), have some magic method for separating the gems (like tptacek claims to possess) or it is just too risky to consider them.