It is not even remotely a feature of all growth-focused businesses. For example, Slack is a growth focused company that uses a subscription model for revenue a

It is not even remotely a feature of all growth-focused businesses. For example, Slack is a growth focused company that uses a subscription model for revenue and has no incentive to maximize time spent in their App. You are correct that advertising, microtransactions and gambling lead to very similar business model incentives.