Distinguishing that from a higher R0 is difficult, as there are few areas of the planet that are not full of vaccinated and prior infected people at this point.
Sure it is. But there are some very smart, skilled people out there with data.
If I have to point an issue at your argument, it is this - Delta spread over the world over the course of half a year, through a population that still had plenty of unvaccinated people. The US, for example, had 40% to 50% vaccination rate during the period of Delta's rise to dominance, not high enough to really slow it down all that much.
If Omicron evades vaccines, that just means it, too, is spreading through a largely vulnerable population. But it came to dominance over the course of about one month. Which suggests that it really is worse than Delta, vaccine or not.
This is supported by research showing that Omicron spreads so rapidly by reproducing
ungodly fast in the bronchi (this is measurable - it reproduces about 70 times faster than Delta in these tissues). Meaning, it is doing to Delta what Delta did to Alpha - simply massively out-reproducing in the places it counts for spreading the virus.
The fact that we
know it out-reproduces Delta stands against your argument that it is somehow no more infectious. The higher reproduction rate
is part of how infectious it is. It means higher doses of virus per cough and sneeze and breath, meaning we should expect more infection, unless given a very specific reason to expect otherwise.
I know of no such specific reason to think otherwise.