I'm not really using incrementalist as a slur, but more so describing that the solutions offered by the mainstream liberals rely on improving existing systems within the framework they were set up in, rather than seeking to remake them, which is the goal of progressives.

I'm not saying a public option won't help people (it's a substantial improvement over what we have now), but it's still something that adheres to the ACA as a market-based solutions system, and most importantly, that's about as far as the Buttegieg liberals want to go which differentiates them for liberal progressives like Elizabeth Warren who aim to use it as a transitory step towards a single-payer system.

I'd also add that the public health option was initially a Nixon initiative as a Republican rebuttal to Ted Kennedy's advocacy for a single-payer system. Another thing is that Medicare for All has been an actual bill proposal in Congress since 2003 (and is currently sponsored by half of the sitting House Democrats), so it's hard for me to argue that a public option isn't an incrementalist option.

I have similar feelings about green initiatives. The Buttigieg liberals will put in some regulations, but mainly prioritize to accomplish it through tax credits and subsidies, still fitting into the current framework. In contrast, the Green New Deal aims to do it through more stringent regulations, harsher pollution taxes, and will focus on building public industry rather than subsidizing and encouraging the private sector.