AFAIK the main purpose first and foremost was to prevent the health system from collapsing. Everything else was secondary. Take the spike out of the incidence rate to spread hospital admissions out over time.
It would not affect how many got infected, not even deaths directly - the only way to reduce deaths would be if in the meantime better treatments could be developed, more people getting vaccinated, and enough hospital (especially ICU) capacity for the severe cases being available. So death prevention was an indirect effect and not the direct target.
For some strange reason, I rarely see this main target being mentioned in discussions, especially not of the "deniers", for example when they point to "it's my own problem the government should not tell me what to do", neglecting that having to be hospitalized does make it everybody else's problem too.
The question is not the death rate, even if it was exactly the same (which I highly doubt, given that we achieved a significant vaccination rate demonstrably reducing severe cases, and better treatments), the question that the COVID measures should be evaluated against is if we indeed managed out spread out the wave(s) over time. In the end almost everybody will have been in contact with the virus, preventing that never was the goal, only to spread it out over time.
That said, I'm also curious how someone could claim "Lockdowns had little or no impact on COVID-19 deaths". Do they really claim with even more stressed ICUs and more severe cases because of less vaccinations (which only became available later) there would have been the same number of deaths? That sounds more than a bit strange to me.
That said, I'm not at all opposed to critical review of the measures. Many did seem a bit off, for example continuing to limit outdoor movement when it had already been shown that the main problem was prolonged closed-room indoor exposure.
I also see curious patterns when I look at the incidence map of Germany. Right now the southern East German states, the ones with the most opposition to COVID measures, are much lighter (much lower incidence rate) -- https://www.zeit.de/wissen/aktuelle-corona-zahlen-karte-deut... (at the time of posting this link those mentioned states are significantly lighter than the entire rest of the country, for the second time, at other times they were/are deeper red)
Just a few weeks ago they were the deep red ones. The newspapers only reported when those regions had worse numbers, now for the second time their numbers are much better than that of the rest of Germany for the second time and again not a single mention of it in the media. I don't want them to interpret it, I think that remains open without good study, I'm only talking about merely even just mentioning the fact, but nothing. That is quite some selective attention to only the negatives.