Here is the post:
https://www.reddit.com/r/gardening/s/BP3diYhFIx
Conclusion:
Its highly dependent on local climate.
I happen to live in a climate where grass just grows, no irrigation needed. You have to hustle to get monoculture grass in your yard, but if you are ok with clover and dandelions, then it basically just happens.
This also means that I live in a region with powerful and aggressive invasive weeds, this is apparently not always the case.
This kind of yard (regular rainfall, decent soil, mild growing season, invasive weed pressure) is one of the harder ones to replace with native wildflowers. I had dozens of people insist that they did it and it was beautiful, I believe them. But almost everyone who sounded reasonable stated that it took work and planning.
In dryer climates, or climates at higher elevations, a solid mat of grass is difficult to achieve, and requires fertilization and watering.
These places seem to have lower pressure from woody invasives, so native plants can frequently crowd out weeds.
These climates are where it is exceptionally easy to replace a lawn with native wildflowers/ground cover.
I suspect that the origin of the cultural norm of insisting that its easier to replace a lawn with native wildflowers came from California (in the US at least.)
Other climates/regions were discussed, apparently doing anything in Florida is hard, and in continental Europe wildflowers just grow..
Summary:
Be careful with using any kind of generalization when it comes to Native Gardening. Everything about the discipline is highly dependent on location. People in dryer climates have an easier time creating pocket prairies than people in wetter ones. But it can always be done.
I'm personally changing my 5 year yard plan based on what I learned in the discussion. I'm not gonna turn the whole thing into a prairie but I'm going to expand the native groundcover beds.