Daily active users is a traditional, industry-standard, metric to measure product usage.
If your mobile game has 100k daily active users, it is a popular app. It doesn’t mean it will stay like this forever. It doesn’t mean that it is growing.
Product KPIs like page views and avg. time on page are crucial, but it tells you half of the story about your product’s growth. They are necessary, but alone, they are just vanity metrics.
Growth KPIs show you another dimension: they tell you the full picture of whether your product is declining, stalling, or growing.
They lead you to ask you the right questions: is my product user base growing? Do they feel happy with my product? Are they coming back and spending more time on it?
If you look at the GA chart above, people coming back to the product are spending around the same amount of time (except for some spikes.)
This is not necessarily bad. It depends on what you consider as growth: do you want the users to come back and spend more time, or the same amount? It is definitely bad if they are not coming back.