Google has an infinitely-larger community; a local community is not sufficient in dense areas where businesses are opening and closing every day. France has the third largest OSM community and yet some neighborhoods of its largest cities are full of outdated businesses.
That being said, I switched to Organic maps years ago. For 90% of places I go, it turns out I go to them repeatedly day-to-day, so I added them to the map the first time and update them when I go there and the hours have changed. Then they're on the map the rest of the time when I need to look up hours or what not so I rarely have anywhere around here that I go to that's not on the map anymore. When I do, I add it and next time it's on there and it works well enough 99% of the time.
For example, bicycle routing in my area was unreliable, because it would try to route me over rough trails. Just adding a few tags improved the experience dramatically. And then it was fixed not only for me, but everybody else too.
Meanwhile, other people fixed other annoyances, and the map works better across many areas. Google instead decides to hide things that interest me, and shows sponsored places I don't care for. I have zero recourse.
This works for routing, but doesn’t apply to businesses: for the bare minimum you have to add one or two tags (type + name), to make that more useful you have to add the opening hours and ideally the website. Now multiply this by 60,000 (the number of businesses in Paris, France). By the time you’ve finished your neighborhood some businesses you checked last month are already closed and some new ones already opened. Go on holidays? Too bad, you have to start over again when you come back. Trust me, I’m contributing almost every day and I can’t keep the pace.
And I think even partially complete OSM is helpful. If I add just one ATM, that can already help somebody looking for one. That might even be me, when I know it's there somewhere, but not exactly where.
community size absolutely does not matter, it's the activity. a local active community of 2 active persons for every 260 residents is sufficient
That would be huge. For a city with 2M inhabitants, that would mean 8k active contributors. Remember that there are ~40-50k active OSM contributors in the whole world.