Post hoc, ergo propter hoc.
It's not a "holiday gathering spike". It's literally the same respiratory pathogen pattern we've seen for as long as we've bothered to look: in the winter, as we go inside and the air becomes cool and dry, respiratory infections go up. The viruses evolved to work this way, because it's a great survival strategy when your host is a social animal that doesn't/can't live outside in the cold.
It happens in parts of the world where Christmas and Thanksgiving aren't a thing (see Japan and China and Korea right now). It happens on the opposite schedule in the lower half of the planet (even where Christmas and/or Thanksgiving are a thing).
This impulse to blame/scold people for a natural phenomenon is unnerving.
Cold/dry air: most respiratory viruses we've looked at survive for longer in cold, dry, dark air.
This winter is the cause the please explain Japan which had it's biggest spikes in summer
Comparing the absolute magnitude of these spikes is fraught, because they depend on the number of tests being conducted, (which was rapidly increasing over the course of last year), as well as the many other behavioral changes that were happening at the same time.
Yeah, but as far as our governments will share more information on this, this SARS-CoV-2 virus was invented by people in a lab, and it escaped from a lab, due to human error.
Covid used to be novel. Now it's endemic and mutates multiple times per year. It's looking more and more like Covid will be with us for decades if not forever, just like the flu and the common cold.
In the world of security, you grow up, leave behind the simple binary descriptions, and assess impact of event and threat you're defending against.
This applies to disease safety as well. It's not just 'inevitable' or 'preventable', but there is a difference between getting sick once a year and getting sick every month. Between working in a hospital and working from home. Between being sick by yourself and spreading it to your extended family.
There is a risk assessment to be done, and calculated measures to be taken.
However, once the disease is characterized, you have effective treatments and protocols for the most sick, and you have decent rates of vaccination and recent infection... needs shift.
The critical factor is {max hospital ICU capacity} + 1 more seriously ill person, and when you're dealing with exponential growth rates and a virgin population, that can be hit pretty easily.
The fact that we didn't (in most parts of the world, for most of the time) is a triumph of modern health policy.