It is not surprising that some people do not know this, as the president has recently said he would sign an EO mandating this, even though it is already law[1]. It’s unclear if he is unaware that the ACA already includes this mandate or if it is a deliberate misinformation campaign.
[0] https://www.hhs.gov/healthcare/about-the-aca/pre-existing-co...
[1] https://www.usatoday.com/story/news/politics/2020/08/08/trum...
Bernie favoured the radical overhaul it frankly needs. But if you can't get that, any progress is still progress.
https://stateofreform.com/news/california/2019/07/california...
Why expect more progress at the federal level?
Healthcare for the Democrats is like guns for Republicans. It's too useful as a wedge issue they can use to scare voters to the polls. They're more interested in yelling about what the other side will than passing the legislation they promise.
Politics is a marathon not a sprint. It may not happen in 2020, but it's certainly closer to reality than it has ever been.