What's the purpose of uncapping budgets to fully capture AI'

Google’s AI only works in newly created campaigns with budgets of at least $1,000 per day.
Campaigns that incorporate Google’s AI spend more of their budget to reach more customers.
When a campaign’s budget is limited, a Smart Bidding strategy will convert back to manual bidding.
Campaigns need enough flexibility in the budget to allow Google’s AI to work to its fullest potential.

What’s the purpose of uncapping budgets to fully capture AI’s benefits?