There actually are a ton of these sorts of events that experience moderate success. Root 107, al fresco, 124th market on Thursdays and Sundays, DT farmers market, open streets. Then all the one off events in pocket parks, bike tours, art exhibitions, etc.
I think following the right social channels is helpful, explore edmonton, dba, edify, etc can keep us in the loop.
But I do think these small events are different than permanent attractions like a Rec Room, favourite bars, movie theaters, etc.
One thing I've seen in places like Vancouver and NY too is how impactful religious gatherings are in downtowns. Because the community often draws from all over a city, especially smaller groups like Jewish or Hindu communities. So if they have gathering places in downtown, people from all over the city drive and train in to gather. And then that also brings children and people looking to enjoy food often as well.
I find our downtown has very few active or large religious groups. A few historical buildings, but there are mosques and temples and churches in the suburbs that see 1000-5000 people every weekend. In Vancouver and NY you see thousands of people downtown for religious stuff on weekends. In edmonton, its empty on Sundays. And I think religious gatherings can compliment downtown social scenes well as they're often mornings/afternoons, and for Christians, Sundays. Whereas nightlife, bars, festivals are more afternoon and evening/night.
Just another observation of what edmonton doesn't have vs some other really lively DTs!