I think one of the primary divergences of thought happening here is whether H1B is indeed a temporary visa or whether it was meant to be a stepping stone to a green card.
H1B is only 36 years old. The Immigration Act of 1990 always meant it to be a temporary status, which is why it is so easily imperiled.
Yes, it's temporary, but the 1990 act explicitly established dual-intent, which clearly made the visa eligible for adjustment of status under INA 245. Nobody is really debating that fact, but the announcement memo is also not clear about what they're going to try to do in terms of actual administrative process.
Part of the noise around this topic is that the administration just announced something vague with no detailed guidance, which leaves the door open for bad-faith interpretations by everyone.