On the hand I know exactly what you mean about Greenwald and Taibbi (and so many other neoreactionary media folks), but it's also where I get great content from economists (Noah Smith, Claudia Sahm, Doomberg) and technologists (our own Simon Willison, Gergely Orosz, Molly White).
The media folks are clearly escaping scrutiny and playing to their base, but there are many excellent Substackers in other fields!
I believe you, but Substack is clearly trying to appeal to that same base[1]. I'm sure there's fine content on there somewhere, but Substack's brand is so unappealing to me I'm just not interested in supporting the company.
How are they escaping scrutiny? They hardly seem interested in hiding what they believe seeing as how they are both very active on Twitter. And whose scrutiny do you consider them anxious to avoid? Their opponents know very well what they are saying. This whole framing reeks of the kind of censoriousness which they both spend a lot of time railing against.
The media folks are clearly escaping scrutiny and playing to their base, but there are many excellent Substackers in other fields!