It's difficult to compare countries see nordic countries There are more also we had no protective gears for the care workers in the elderaly
It raises a lot of interesting issues but gets some wrong.
Sure, much we don't know, but by now much we do.
Ignoring what it says about what governments say (it depends which country you are in):
(1) True, deaths at any time depend on infection rates which vary enormously. And people tend only to look at deaths
(2) False, the vaccine maybe does not do much good against other strains. We have good figures for VE against delta. VE against infections is not great but still a bit worthwhile in terms of reducing infections. Delta is so infectious it will not be stopped by vaccines alone, practically. VE against serious infection and death is excellent against delta and stays very good for at least 6 months, after which a booster shot puts it back to excellent. By excellent I mean 20X less chance of serious disease. We don't know exactly how immunity decays from vaccination over long times.
Those two facts are enough. It does not matter that you need people to get covid as well to achieve herd immunity. If they are vaccinated first the death toll is 5X - 20X less. Younger people have lower risks anyway, but also have higher relative protection from the vaccine. Which is not the point - absolute reduction in risk is what matters.
Once everyone who is going to catch COVID has done so, then COVID becomes a less severe disease, especially if we have the right drugs to reduce long COVID etc.
Vaccines reduce death getting to that nice place, and also delay it, so that more drugs are well understood thus further reducing harm.
The tone of that link is more "vaccines are a hysterical over-reaction". They do at the margins reduce R which is why governments are keen on them for young people. They also reduce small absolute risks for young people, which is why doctors are keen on them (at least from say 15 up). But mainly they reduce hospital burden and getting very high fraction of vaccinated in older (> 40) age groups is essential for countries wanting hospitals to operate normally and keep their population alive. You still need vaccination below that - for hospitals - because otherwise a very high peak in infections and hospitalisation can still occur, even though the individual risks are small for younger ages. And small does not mean 0.
I do not know how under reported, but I do noticed that the his collegues told they didn't know how to do this. Now he and his colleuges are probably young and the senior doctors may know and make sure there are good reporting, still I would do a research project to investigate this. To understand this guy, you need to see more of his post. His not an anti vaccer, but he have discovered a lot of overuse of medicins and also discusses problems in the system we setup to do our medics. One thing that is obvious are that the test procedures medicines can be gamed by the medical companies and they do seam to take advantage of this, another fact and my personal pet argument is the disatstrous oversubscription of opioids in USA, But there are more subtle discoveries that he discusses such as doctors seam to be bad at basic probability theory. Also he is very keen on teaching the scientific method and how to read studies properly.
I think that when you are arguing that ER's on places that does not take vaccines ore over crowded, then note that most of them probably are old stubborn people that does not take the jab, but what he is arguing is that the vaccinating the younger population may be less of a slam dunk. Personally I think young people should take the jab. First of all, we will have new strains with or without vaccination and new strains may start to kill the young ones, Also having the jab seam to still allow infection but hinder death and icu so for the virus that's even better that having no vaccine and the host is killed e.g. there is in reality not an especially big push for the virus to mutate compared to natural immunity. And if the virus starts to mutate and attack also young people then we are prepared if they already are vaccinated. The negative, like long term effects i an unknonw as well and also as you say, it is more and more clear that the side effects really is not that bad. Things really are complicated if you dig into it and I understand this guy's position. And then we have all the madness out there that destroy's the scientific discussion with people flocking to sides and start to stop thinking and use their but to argue. I'm too old to care as I said before, but this gives a lot of understanding of why social media starts to sensor sensible discussions and that you may find a good report that wants to argue against the common rejected.