> In addition means we need a lower rate for herd immunity

No, it actually doesn't, the math functions differently than what is naively believed. See:

https://statmodeling.stat.columbia.edu/2020/08/03/math-error...

The R0 would have to be corrected to the higher value, which would mean that the herd immunity threshold for the susceptible part of population would have to be higher(!)

Also, even among completely asymptomatic a high viral load is surely observed, implying that they aren't "immune" in the sense that they aren't the ones who continue to spread the infection -- but even for that, more research is needed.

Which means, until we know more, that those who are in danger aren't less in danger at all until they get a vaccine. With all the consequences we already know, like in the states which were strongly hit.

> the models of exponential growth was unfounded

I don't believe anybody ever claimed that the exponential growth would be indefinite. However, exponential growth through the susceptible part of population in one important phase of the spread (before any interventions are taken) was indeed a good enough approximation of what was observed.

Edit: re: the comment below: "it still means that herd immunity is easier and faster to achieve" -- no, not necessarily, see what I wrote about the "asymptomatic." For all we know at this moment, they get the virus and they spread it. If they just don't get sick it is then different from them not being involved in the transmission. And if some amount of people are identified who can't get it, the result can still mean "for two more years it has to be like it was up to now."

Edit 2: re the comment below: "That maths you link to literally says that the threshold for herd immunity among the entire population is indeed lowered." No it doesn't, not in the sense "it is better". Try to work from R0 = 2.7 which was observed. Assume 50% can't even spread. The R0 for the remaining 50% is then not 2.7, but has to be scaled up to 5.4(!) Which means, e.g. that the 90% of the 50% have to become immune to reach the herd immunity. And if up to now e.g. 10% of these were infected in past 6 months, that means 6 months * 8 = 4 years more to go. Whereas, when no 50% "immune" population exist, if with given R0 2.7 the threshold is e.g. 60%, and we have 10% infected, we have only 5 times 6 months to go, i.e. 2.5 years(!). You see, it's nothing so obvious like one likes to believe. Like Ed Young said: "Immunology Is Where Intuition Goes to Die." Search for the article (it's not about this calculation, but about how simple mental models don't work with immunology on other levels too).

The herd immunity threshold is dependent of R0, and that is exactly what they try to explain in the post. But like I've said, we don't even know how many of "asymptomatic" are part of all equations. And which equations are the right ones. The "right" models could be even more complex than what I've used here.

Edit 3: re: Citing Judith Curry. Judith Curry, the only qualification having from being one of the most favorite "experts" to be cited by climate deniers. But what she claims is still wrong: https://www.skepticalscience.com/skeptic_Judith_Curry.htm