The answer to that for most people is pretty much yes. 50/21 at 80rpm is 10 mph. Even in most head winds, most folks can hold 10mph.

And most "climbs" are 60-70 vertical feet and over in less than 2 minutes. If you can't do those in the big ring, you're going to get dropped on most group rides.

Only time I would use the small chain ring would be a massive headwind, warming up/cooling down, recovery ride.